RAM Suction Cup Mounts

RAM makes some of the best suction cup mounting hardware for windshields, glass and other smooth nonporous surfaces, but a RAM suction cup mount is not one product. It is a system, and picking the right pieces is where most buyers get stuck.

A suction cup by itself only gets you attached to the glass. Depending on what you buy, you may still need a double socket arm, a ball adapter and a device holder before you have something to hold your phone, GPS or tablet. RAM also sells complete kits that include everything you need for a specific device.

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Quick answer: Most phones and automotive GPS units are well served by a B-size RAM Twist-Lock system with a 1-inch ball. Pick the arm length based on how far the device needs to reach. Larger tablets can often work with a single B-size suction mount when they fall within RAM’s published weight limits, while dual-suction and C-size systems give you better support for bigger or more demanding installs.

Table of Contents

How a RAM Suction Cup Mount Works

RAM’s Twist-Lock suction bases are built for vehicle windshields and other smooth, nonporous surfaces.

The common RAM windshield system breaks down into four pieces:

Suction cup base: attaches the system to the glass.
Ball: determines which RAM socket-arm family the mount uses.
Double socket arm: handles positioning and adjustment.
Device holder: grips the phone, GPS, tablet or other electronics.

That last part is where most confusion starts.

A product like the RAM-B-166U gives you the suction base, B-size ball system, medium double socket arm and diamond adapter. It does not give you a phone holder.

If you already own a RAM cradle, that is not a problem. If you are starting from scratch, buying a complete kit such as a RAM X-Grip suction cup mount saves you a step.

For a full explanation of how RAM balls, arms, bases and holders fit together, see our RAM Mount system guide.

Best RAM Suction Cup Mounts and Bases

Mount	Best For	Configuration
RAM-B-166U	Building a phone or GPS mount	3.3-inch suction cup, B-size ball, medium arm, diamond adapter
RAM-B-166U-A	Short, stable windshield installations	3.3-inch suction cup, B-size ball, short arm
RAP-B-166-2U	Compact low-profile installations	2.75-inch suction cup, B-size ball, compact arm
RAM-B-166-UN10U	Large phones	Complete X-Grip phone mount
RAM-B-189B-202U	Larger devices and dual-suction builds	Two 3.3-inch Twist-Lock cups with B-size ball
RAM-B-224-1U	Adding suction to an existing B-size RAM setup	3.3-inch Twist-Lock cup with B-size ball

RAM-B-166U: Best Starting Point for a Modular Windshield Mount

The RAM-B-166U is probably the RAM suction mount most people run into first.

It combines:

a 3.3-inch RAM Twist-Lock suction cup;
a B-size 1-inch ball;
a standard medium-length double socket arm; and
a diamond-shaped mounting plate.

The medium arm gives you about 3 inches of socket-to-socket length, providing more positioning room than the short-arm versions.

This is a solid pick if you already own a RAM device cradle or if you want to build your own system piece by piece.

Important: RAM-B-166U does not include a phone or GPS holder. The diamond adapter attaches to a compatible RAM cradle or holder, sold separately.

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RAM-B-166U-A: Better When You Do Not Need Much Reach

The RAM-B-166U-A uses the same 3.3-inch Twist-Lock cup but swaps in RAM’s short B-size arm.

Socket-to-socket length drops to about 1.75 inches, down from roughly 3 inches on the medium arm.

That matters more than it sounds like it should. The farther a phone or GPS sits from the windshield, the more leverage it puts on the mount, and longer arms tend to exaggerate vibration and movement.

Real-world rule: Do not buy a longer RAM arm just because it offers more adjustment. Use the shortest arm that still puts the screen where you can see and reach it comfortably.

For more detail, see our guide to RAM B-size arms.

RAP-B-166-2U: The Compact 2.75-Inch Alternative

The RAP-B-166-2U is different from the RAM-B-166U, but maybe not for the reason you’d expect.

It uses a smaller 2.75-inch Twist-Lock suction cup and a compact B-size arm, which gives the whole assembly a smaller footprint on the windshield.

What it does not mean is that RAM built it simply as a weaker phone-only system. It still runs on the B-size 1-inch ball system and is intended for lighter B-size mounting applications.

Pick this version when you want a more compact windshield installation without giving up the modular RAM B-size ecosystem.

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For a Phone, a Complete X-Grip Kit Is Easier

If you do not already own RAM components, buying the suction base, arm and holder as separate pieces is more work than it needs to be.

RAM sells complete Twist-Lock phone kits instead. One of the useful versions is the RAM-B-166-UN10U X-Grip Large Phone Mount, which combines:

a 3.3-inch Twist-Lock suction cup;
a medium B-size double socket arm; and
RAM’s large X-Grip phone holder.

The larger X-Grip is designed for bigger phones, including many devices used with protective cases. Always check RAM’s current holder dimensions against the phone with its case installed before ordering.

This is a much more accurate example of a complete RAM phone mount than the RAM-B-166U above. With the RAM-B-166U, you still need to add the appropriate holder.

RAM also offers X-Grip configurations for narrower phones.
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Buying tip: If you are starting from scratch, a complete RAM phone kit is usually easier than buying a suction assembly and then trying to determine which holder, ball adapter and hardware you still need.

Single Suction Cup or Dual Suction Cup?

A full-size tablet does not automatically need two suction cups.

RAM makes single-suction tablet systems, and they can work well when the tablet and installation remain within RAM’s stated limits.

So why go dual suction at all?

Because two suction cups give you a wider mounting footprint and spread the load across two attachment points instead of one.

The RAM-B-189B-202U pairs two 3.3-inch Twist-Lock suction cups with a B-size 1-inch ball. It can serve as the foundation for a more substantial tablet or device mounting system.

Dual suction earns its keep when:

the tablet is relatively large;
the device sits farther from the glass;
the installation sees more vibration;
you want redundancy from a second suction point;
the mount stays in place for long stretches; or
a larger cradle creates more leverage than a phone holder would.

RAM also makes C-size systems using a larger 1.5-inch ball for heavier-duty applications.

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For complete tablet mounting options, see our best car tablet mounts guide.

B-Size vs C-Size Matters More Than Most Buyers Realize

RAM systems are identified in large part by ball diameter. For windshield installations, you will commonly encounter these two sizes:

B size: 1-inch ball.
C size: 1.5-inch ball.

Phones, GPS receivers and many tablet installations use B-size components.

C-size hardware is physically larger and designed for more demanding mounting applications.

The important thing is to stay within the same RAM ball ecosystem when assembling a mount. A B-size double socket arm is designed for B-size balls. A C-size arm is designed for C-size balls.

If you are not sure which system you already own, see our RAM ball size guide before ordering additional pieces.

What About the Suction Cup Base by Itself?

Sometimes you do not need another complete suction mount.

The RAM-B-224-1U pairs RAM’s 3.3-inch Twist-Lock suction cup with a B-size 1-inch ball.

Unlike the RAM-B-166U, it does not include a double socket arm or diamond mounting plate.

That makes it an excellent choice when you already own:

a RAM B-size double socket arm;
a RAM phone, GPS or tablet holder; and
the appropriate ball adapter for that holder.

You can simply add the suction base and reuse the rest of your RAM system.

This modularity is one of the biggest advantages of RAM products. A holder and arm that normally live on a motorcycle, boat, truck or desk setup can often be moved to another RAM base without replacing the whole system.

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Complete Mount or Individual RAM Components?

This is probably the easiest way to avoid buying the wrong product.

Buy a complete RAM kit if:

you are starting from scratch;
you only need the mount for one device;
you want to know that the base, arm and holder are already matched; or
you do not plan to move RAM components between different vehicles.

Buy individual RAM components if:

you already own B-size or C-size RAM hardware;
you want a different arm length;
you want to move one holder between several mounting bases;
you need an unusual mounting position; or
you enjoy building a mounting system around your exact installation.

For many long-time RAM users, buying the components individually makes sense because they already have a collection of arms, balls and holders.

For a first-time buyer who simply wants a phone on the windshield, a complete kit is easier.

Where Should a RAM Suction Cup Be Mounted?

A Twist-Lock suction cup works best on clean, smooth, nonporous material, and vehicle glass is the obvious target.

Before you install one:

Clean the mounting area thoroughly.
Remove grease, dust and interior-detailing residue.
Let the surface dry.
Press the suction cup firmly against the surface.
Engage the Twist-Lock mechanism.
Check the mount before you trust it with an expensive device.

Do not expect reliable suction directly on a heavily textured dashboard.

If you want to place the mount on a dashboard instead, a smooth adhesive mounting disk can give the suction cup an appropriate surface to grab.

Installation tip: Clean the glass before installing the mount and avoid placing the suction cup over printed dots, heavy tint edges or other irregular surfaces that prevent the entire cup from sealing evenly.

Common RAM Suction Mount Mistakes

Buying RAM-B-166U and expecting a phone holder. It needs a compatible cradle or holder.
Choosing by suction-cup diameter alone. Ball size, arm length, device weight and mounting geometry all matter.
Using an arm longer than you need. More reach also means more leverage and usually more movement.
Mixing ball sizes. B-size and C-size components use different ball diameters.
Ignoring the case when measuring your phone or tablet.
Mounting directly to a textured dashboard. Suction cups need a smooth surface to work properly.
Assuming one suction cup cannot hold a tablet. RAM offers single-cup tablet systems for appropriate applications.
Assuming dual suction always means C size. Dual-suction configurations are available in more than one RAM ball-size family.

Windshield Mounting Laws

Before you install any windshield mount, check the laws where you drive.

Some states regulate where devices can attach to the windshield or how much of the driver’s field of vision they can obstruct.

That does not automatically rule out suction mounts. Placement rules vary considerably by jurisdiction, and legal placement can be just as important as choosing the right mount.

See our guide to windshield GPS mounting restrictions for more.

Are RAM Suction Cup Mounts Good for Motorcycles?

Not really.

Motorcycles give you far better mechanical mounting points, including handlebars, brake or clutch reservoirs, mirror stems and other solid attachment locations.

For a motorcycle, a mechanically attached mounting base makes far more sense than relying on windshield-style suction.

See our motorcycle mount guides for better options.

Which RAM Suction Cup Setup Should You Buy?

For most buyers, it comes down to this:

Building your own phone or GPS system: the RAM-B-166U is an excellent B-size starting point.
Want less movement and do not need much reach: consider the short-arm RAM-B-166U-A.
Want a smaller windshield footprint: consider the 2.75-inch RAP-B-166-2U.
Starting from scratch with a phone: a complete X-Grip Twist-Lock kit is easier than piecing together the base, arm and holder individually.
Already own RAM B-size parts: the RAM-B-224-1U suction base may be all you need.
Mounting a larger tablet: check RAM’s published limits and consider the dual-suction RAM-B-189B-202U or a larger C-size system when the size, weight or mounting geometry calls for it.

Related RAM Mount Guides

Bottom Line

RAM Twist-Lock suction mounts are excellent windshield hardware, but picking one based on suction-cup diameter alone misses the point.

For most phones and GPS devices, the B-size 1-inch RAM system is where you should start. From there, match the suction base, arm length and holder to your installation.

The RAM-B-166U is one of the most useful modular starting points, but it is not a complete phone mount on its own. If you want something ready to use out of the box, a complete RAM X-Grip Twist-Lock kit makes more sense.

If you already own RAM hardware, the RAM-B-224-1U lets you add a windshield suction base without buying another arm and holder. For larger tablets and more demanding installations, the dual-suction RAM-B-189B-202U gives you two attachment points and a much broader mounting footprint.

The key is to think of RAM as a system rather than a single mount. Match the ball size, arm length, suction base and holder to the device you are mounting, and you end up with a much better setup.