RAM Mount X-Grip holders are popular because the same basic mounting system can hold everything from a smartphone to a large tablet. The part that gets confusing is that RAM makes several different X-Grip sizes, and the larger tablet versions do not attach to the RAM system the same way as the phone versions.
Choose the wrong X-Grip and your device may not fit at all. Choose the wrong RAM ball or socket arm and the pieces may not connect.
This guide explains the current RAM X-Grip sizes, their correct fit ranges, which models include a ball, and what additional hardware you may need.
Table of Contents
RAM Mount X-Grip Size Chart
| X-Grip Holder | Width Range | Maximum Depth | Mounting Connection | Best For |
|---|---|---|---|---|
| RAM-HOL-UN7BU | 1.875″ to 3.25″ | 0.875″ | 1″ B-size ball included | Standard phones |
| RAM-HOL-UN10BU | 1.75″ to 4.5″ | 0.875″ | 1″ B-size ball included | Large phones and bulky cases |
| RAM-HOL-UN8BU | 2.5″ to 5.75″ | 0.875″ | 1″ B-size ball included | 7″ to 8″ tablets and similar devices |
| RAM-HOL-UN9U | 6.25″ to 8.1″ | 0.875″ | Ball not included | 9″ to 11″ tablets |
| RAM-HOL-UN11U | 7.25″ to 8.75″ | 0.875″ | Ball not included | 12″ to 13″ tablets |
Important: Measure the device with its case, sleeve, or skin installed. Do not select an X-Grip based only on the advertised screen size of the phone or tablet.
How the RAM Mount X-Grip Works
The Mount X-Grip cradle uses a spring-loaded X-shaped mechanism with four rubber-capped gripping points. Pull the arms apart, place the device between them, and spring pressure closes the arms around the device.
The open design leaves most of the screen, charging port, cameras, and controls accessible. Because the holder adjusts mechanically rather than using a phone-specific shell, one X-Grip can often survive several phone upgrades.
That does not mean every X-Grip fits every device.
Width and thickness still matter, and the location of side buttons can also affect how well a particular phone sits between the X-Grip arms.
For phones, RAM includes an optional rubber tether with the current X-Grip holders. We strongly recommend using it on motorcycles, ATVs, off-road vehicles, boats, bicycles, and other applications where losing the device would be a very expensive mistake.
RAM-HOL-UN7BU: Standard RAM Mount X-Grip Phone Holder
The RAM-HOL-UN7BU is the standard phone-size X-Grip and one of the most common RAM holders.
It accepts devices:
- Width: 1.875″ to 3.25″
- Maximum depth: 0.875″
The measurement that sometimes causes confusion is 0.875″. That is the maximum thickness of the phone and case. It is not the minimum phone width.
The UN7BU comes with RAM’s 1-inch B-size rubber ball attached to the back. That means it connects directly to a RAM B-size double socket arm.
This is an excellent choice for phones that fall comfortably inside the stated dimensions, but do not assume that a phone fits just because it is marketed as a standard-size model. Measure it with the case installed.
RAM-HOL-UN10BU: Large X-Grip Phone Holder
The RAM-HOL-UN10BU is the larger phone version.
Its fit range is:
- Width: 1.75″ to 4.5″
- Maximum depth: 0.875″
That wider adjustment range makes the UN10BU useful for oversized phones and phones in thick protective cases.
Notice that the minimum width is slightly smaller than the minimum width of the standard UN7BU. X-Grip sizing is therefore not a simple progression where each larger model starts where the previous one stops.
That is another reason to use the actual measurements rather than choosing based on the words “standard” and “large.”
Like the UN7BU, the UN10BU includes a 1-inch B-size ball on the back and connects directly to a B-size RAM socket arm.
We would not automatically choose the Large simply because a phone is new or expensive. Check the dimensions of your phone and case and use the holder that provides the appropriate fit.
RAM-HOL-UN8BU: X-Grip for 7-Inch to 8-Inch Tablets
The RAM-HOL-UN8BU is the small-tablet X-Grip.
RAM currently specifies:
- Width: 2.5″ to 5.75″
- Maximum depth: 0.875″
It is designed primarily for small tablets and similar devices.
RAM also lists height considerations at the extreme ends of the width range, so this is one product where checking only width is not enough if your device is unusually narrow or wide.
The UN8BU includes a 1-inch B-size ball, so it works with B-size RAM arms without requiring a separate ball adapter.
It also includes a device tether for added security in outdoor and rough-use applications.
RAM-HOL-UN9U: X-Grip for 9-Inch to 11-Inch Tablets
This is where the RAM Mount X-Grip lineup changes.
The RAM-HOL-UN9U fits tablets with:
- Width: 6.25″ to 8.1″
- Maximum depth: 0.875″
- Maximum height with optional supports installed: 10.25″
The optional side supports are intended to add security in rough environments. Without those supports, RAM does not specify the same 10.25-inch height limit.
More importantly, the UN9U does not include a ball.
The back of the holder provides mounting patterns that allow you to add the appropriate RAM ball plate for your installation.
This matters because you are not forced into one ball size.
A UN9U can be configured around a B-size system for lighter-duty applications, or it can be paired with larger RAM hardware such as the C-size system for applications where the larger tablet and rough environment justify heavier mounting components.
So if you already own RAM hardware, do not assume the bare UN9U will clip directly into your existing arm. First determine what ball adapter is attached to the holder and make sure its ball size matches the socket arm.
RAM-HOL-UN11U: X-Grip for 12-Inch to 13-Inch Tablets
The RAM-HOL-UN11U is the largest X-Grip in this group.
RAM specifies:
- Width: 7.25″ to 8.75″
- Maximum depth: 0.875″
- Maximum height with optional supports installed: 10.25″
RAM lists compatibility with devices including several generations of the 12.9-inch iPad Pro and newer 13-inch iPad models, but dimensions should still be checked if the tablet is inside a case.
Like the UN9U, the UN11U does not include a RAM ball.
It provides AMPS and VESA mounting patterns on the rear of the holder. You choose the appropriate ball plate and RAM arm based on the installation.
For a large tablet in a vehicle, boat, commercial vehicle, or rough environment, we would pay as much attention to the ball size and arm length as we would to the holder itself. A large tablet puts considerably more load on the mounting system than a phone.
Understanding RAM Ball Sizes
One of the easiest RAM Mount mistakes is assuming that every rubber ball is the same size.
They are not.
For most phone installations, the relevant RAM system is the B size, which uses a 1-inch ball.
Larger installations often use the C size, which uses a 1.5-inch ball.
A B-size ball requires a B-size socket arm. A C-size ball requires a C-size socket arm.
You cannot place a 1.5-inch C ball into a 1-inch B socket arm just because both parts are made by RAM.
This distinction is especially important with the UN9U and UN11U tablet holders because the bare holders do not dictate the ball size. The adapter plate you add determines which RAM socket system you will use.
Phone X-Grips vs. Tablet X-Grips
Here is the easiest way to remember the difference.
UN7BU, UN10BU and UN8BU:
- Come with a ball attached
- Use the 1-inch RAM B-size system
- Connect directly to a compatible B-size socket arm
UN9U and UN11U:
- Do not include a ball
- Use rear mounting patterns for a separate RAM ball adapter
- Can be configured around the appropriate RAM ball size for the application
That distinction gets lost on a lot of product listings and is the main reason we would not describe all five X-Grips as interchangeable versions of the same cradle.
How to Measure Your Phone or Tablet for an X-Grip
Always measure the device in the configuration you will use while it is mounted.
If you normally keep your phone in a case, measure the phone with the case installed.
Check:
- Width at the widest point.
- Thickness including the case.
- Height if you are using one of the tablet X-Grips with support arms.
- Button location to make sure an X-Grip arm will not constantly press a side button.
Do not shop by screen size alone. Two tablets advertised with the same diagonal screen size can have different chassis widths.
The physical dimensions determine compatibility.
Building a Complete RAM X-Grip Mount
An X-Grip is the part that holds the device. A complete RAM installation normally consists of three major pieces:
- Device holder, such as an X-Grip
- Double socket arm
- Mounting base
The base depends on where the device is going.
Common options include:
- U-bolt handlebar bases for motorcycles, ATVs and other tubular mounting locations
- Tough-Claw bases for removable mounting to rails and tubing
- Suction cup bases for vehicle glass
- Fork stem bases for compatible sport motorcycles
- Brake and clutch reservoir bases for motorcycles with limited handlebar space
- AMPS-pattern bases for permanent vehicle and equipment installations
If you are new to RAM Mounts, our RAM Mount assembly guide explains how the holder, arm, ball and base fit together.
A Note About Motorcycle Vibration
The RAM ball-and-socket system provides some shock and vibration isolation, but that does not mean a standard X-Grip eliminates the camera-damage risk associated with mounting modern smartphones on motorcycles.
RAM warns that vibration produced by high-powered motorcycle engines can affect smartphone cameras.
Modern phones may contain optical image stabilization and autofocus components that can be sensitive to sustained vibration.
For motorcycle use:
- Use the supplied X-Grip safety tether.
- Keep unnecessary arm length to a minimum.
- Check that every socket and mounting fastener is tight.
- Consider a dedicated vibration-damping solution if protecting the phone’s camera hardware is a priority.
The tether helps keep the phone from leaving the holder. It should not be confused with a vibration dampener.
Why RAM’s Modular System Still Makes Sense
The biggest advantage of RAM Mounts is not that one X-Grip fits everything. It does not.
The advantage is that RAM separates the installation into components.
You can keep a B-size arm and motorcycle base while changing from one phone holder to another. You can move a compatible holder from a motorcycle setup to a suction cup system in a car. You can add a different base without throwing away the rest of the mount.
Just remember the rule that keeps the system from becoming confusing:
Match the device to the holder first, then match the ball size to the socket arm and application.
If those pieces are correct, the modular RAM system gives you an enormous number of mounting combinations without forcing you to replace the entire setup every time your device or vehicle changes.
Which RAM X-Grip Should You Buy?
For most buyers, the decision comes down to these five models:
- RAM-HOL-UN7BU: standard phones from 1.875″ to 3.25″ wide
- RAM-HOL-UN10BU: larger phones and bulky cases from 1.75″ to 4.5″ wide
- RAM-HOL-UN8BU: small tablets from 2.5″ to 5.75″ wide
- RAM-HOL-UN9U: 9″ to 11″ tablets from 6.25″ to 8.1″ wide
- RAM-HOL-UN11U: 12″ to 13″ tablets from 7.25″ to 8.75″ wide
For the first three, a 1-inch B-size ball is already included.
For the UN9U and UN11U, plan on adding the appropriate ball adapter and matching socket arm.
Measure first and order second. With RAM Mounts, a few seconds with a ruler is much more reliable than guessing from the phone name or tablet screen size.
