If you are building a RAM Mounts setup, the arm is the piece that connects everything together. The base attaches to your vehicle, boat, or handlebar. The cradle or adapter holds your device. The arm sits in the middle and determines how far your device sits from the mounting surface. Choosing the wrong arm length is one of the most common mistakes first-time RAM Mounts buyers make.
This guide covers the three standard metal arms for 1-inch RAM balls, explains the double ball adapter for extra reach, and tells you exactly which arm suits which situation. All of the arms discussed here are compatible with any RAM component that uses the standard 1-inch ball, which is the most common size in the RAM ecosystem.
How a RAM Arm Works
Every RAM arm follows the same basic design. Two cup-shaped halves face each other and are joined by a central screw attached to a flywheel tightening knob. Each half accepts a 1-inch rubber ball. A spring in the middle of most arms holds the halves slightly apart so you can insert the balls without tools.
To assemble, loosen the flywheel so the halves separate slightly. Press one ball into each cup. Tighten the flywheel until the arm grips both balls firmly. That is the entire process. No tools required. Adjusting the angle of your device is just as simple: loosen the flywheel slightly, reposition, and retighten.
Choosing the right arm works hand-in-hand with selecting the correct RAM ball size.
Selecting the right base is just as important as ball size and arm length. See our RAM mount bases guide to understand which mounting style works best for your setup.
The Standard Arm: RAM-B-201U
The RAM Standard Double Socket Arm for 1-Inch Balls is the arm included with most RAM Mounts kits. It is the right choice for the majority of applications and the one you should start with unless you have a specific reason to go shorter or longer.
The overall length is 3.69 inches from tip to tip. The socket-to-socket distance is 3 inches, which is the working extension your mount adds between the base and the device adapter. This arm includes the standard center spring for easy ball insertion. Build quality is solid aluminum with a stainless steel flywheel bolt. It handles the weight of phones, GPS units, and small tablets without flex or drift once tightened.
The Short Arm: RAM-B-201U-A (A-Length)
The RAM Short Double Socket Arm for 1-Inch Balls is designed for low-profile applications where you want the device as close to the mounting surface as possible. It is also known as the A-length arm.
The overall length is 2.38 inches tip to tip with a socket-to-socket distance of 1.75 inches. That is nearly half the extension of the standard arm. This arm does not include a center spring, so you press the balls directly into the cups and tighten. The lack of spring is not a problem in practice since the cups hold the balls in position during tightening.
The short arm is the right choice for motorcycle handlebar mounts where you want your GPS or phone sitting close to the bar rather than extended outward on a long arm. It is also a good fit for tight spaces where a standard arm would push the device too far into the driver’s field of view. Many experienced RAM Mounts users keep a short arm as a permanent part of their motorcycle or bicycle setup.
The Long Arm: RAM-B-201U-C (C-Length)
The RAM Long Double Socket Arm for 1-Inch Balls is the longest single arm in the 1-inch ball lineup. It measures 6 inches from tip to tip with a socket-to-socket distance of 5.25 inches.
This arm is the right choice when you need significant reach between your mounting surface and your device. The most common use case is a windshield suction cup mount in a vehicle with a steeply raked windshield. The long arm pulls the device back toward the driver to a comfortable viewing distance. Without it, a standard arm would leave the device pressed close to the glass and hard to read at a glance.
The long arm also works well on boats and larger vehicles where the mounting surface is far from the driver’s natural sight line. The same center spring and flywheel design as the standard arm makes assembly identical. Because of the extra length, make sure your flywheel is fully tightened before use. A loose long arm has more leverage to shift position than a shorter arm under the same conditions.
Extending Further: The Double Ball Adapter
When even the long arm is not enough reach, RAM makes a Double Ball Adapter that lets you connect two arms together. The adapter has a 1-inch ball on each end. One arm connects to your base, the adapter connects the two arms, and the second arm connects to your device cradle.
Connecting two standard arms gives you about 6 inches of socket-to-socket reach. Combining a standard arm with a long arm gets you close to 8.25 inches. This is enough for most extreme reach situations. Connecting three arms is technically possible but not recommended. Three arms create too much leverage in high-vibration environments like motorcycles and boats and the setup will work loose over time regardless of how tight the flywheels are.
RAM Arm Size Comparison
| Arm | Model | Tip to Tip | Socket to Socket | Best For |
|---|---|---|---|---|
| Short (A-length) | RAM-B-201U-A | 2.38″ | 1.75″ | Motorcycles, bicycles, tight spaces |
| Standard (B-length) | RAM-B-201U | 3.69″ | 3.00″ | Most vehicles, general use |
| Long (C-length) | RAM-B-201U-C | 6.00″ | 5.25″ | Windshields, boats, extended reach |
| Two Arms Combined | RAM-B-230U | Up to ~10″ | Up to ~8.25″ | Maximum reach situations |
More RAM Mounting Guides
Not sure what else is needed? We have a large amount of information in our RAM Mounts Hub.
We have additional guides on RAM Mounts.
- RAM X-Grip Cradles — an excellent addition to hold phones and tablets
- RAM Mount Extensions — extend the length of the mount
- RAM Snap Link Overview — introduction to the Snap Link line
- RAM Motorcycle Break and Clutch Bases — a lesser known but useful location for cameras and phones
- Attaching a Garmin Cradle to a RAM Mount — a solid option for holding your GPS
- Assembling a RAM Mount — dedicated guide to put it all together
Frequently Asked Questions
What is the most common RAM Mounts ball size?
The 1-inch ball is the most common size in the RAM ecosystem and is used in the vast majority of consumer and light commercial mounts. Larger ball sizes exist for heavy-duty and military applications but are not needed for phones, GPS units, or tablets in everyday vehicle use.
Can I mix metal and plastic arms in the same setup?
Technically yes, but we do not recommend it. The weakest component determines the strength of the entire setup. If you are using a metal base and metal cradle, a plastic arm in the middle becomes the failure point. Choose all metal for any application involving vibration or heavy devices.
How tight should I tighten the flywheel?
Tighten firmly by hand until you feel solid resistance. You should not be able to reposition the arm without deliberate loosening. Do not use tools to overtighten as this can crack the composite cup halves over time. Hand tight is the correct standard for RAM arms.
Will RAM arms work with non-RAM components?
RAM arms only work with RAM balls. The 1-inch ball is a proprietary RAM standard and is not cross-compatible with other mount brands. All three components in your setup, including the base, arm, and cradle adapter, need to use the same RAM ball size.
What is the difference between the B and C size RAM systems?
This article covers the B size system which uses 1-inch balls and is the standard consumer and light commercial lineup. The C size system uses 1.5-inch balls and is designed for heavier devices and more demanding environments like large tablets in commercial vehicles. C size components are not interchangeable with B size components.
