This is a foundation component: the same compact 2.43″ × 1.31″ diamond plate as RAM's B Size version, but topped with a heavy-duty C Size ball for larger devices and rougher environments. Bolt it directly to a flat surface, or use it as an adapter for a cradle drilled to the diamond AMPS pattern.

Features

• Diamond plate features industry-standard AMPS hole pattern and measures 2.43″ × 1.31″
• 1.5″ C Size ball is compatible with any C Size RAM double-socket arm; ball-and-socket technology allows near-infinite adjustability
• Made of powder-coated, marine-grade aluminum for durability and reliability in the most demanding environments
• Backed by a lifetime warranty

How RAM's modular system works

Every RAM mount is built from up to three parts that click together, and the same parts mix and match across RAM's entire catalog:

• A base — clamps, bolts, or straps onto the vehicle (a rail, a roll bar, a dash, a windshield, or a device's own housing).
• An arm — connects two RAM balls together. It locks at any angle, so once mounted you can tilt, rotate, and reposition the device freely, then lock it firmly by hand.
• A cradle or holder — grips the specific device (tablet, phone, GPS unit, camera).

Not every product includes all three parts — some are just the base, some bundle a cradle, some are a complete kit. Further down this page we say plainly which parts this specific product includes, so you know exactly what you're getting and what, if anything, you'd need to add.

The ball size determines what it can carry. RAM uses five ball sizes, each rated for a different weight and duty class:

• A Size — rarely used; costs more to make than B Size but carries less. Reserved for small, low-profile items like security cameras where bulk matters more than capacity.
• B Size (1″ ball) — RAM's most common size, standard duty. This is what RAM recommends for phones, GPS units, and light tablets in normal use.
• C Size (1.5″ ball) — heavy duty. Used for larger tablets, handheld computers/scanners, CB radios, and anything mounted somewhere that gets a lot of vibration or shock — exactly the case in a tractor, ATV, or UTV cab.
• D and E Size — reserved for large monitors and specialist/military equipment; rarely needed outside those cases.

This product uses a C Size ball (1.5″ / 38 mm) — heavy duty, meant for larger tablets, handheld computers/scanners, and anything mounted somewhere that takes real vibration, exactly the case in a tractor, ATV, or UTV cab. If what you're mounting is a phone or a light GPS unit, the B Size diamond base (RAM-B-238U) is the lighter match.

Rule of thumb: if the mount will live somewhere that's frequently jostled, vibrated, or under constant load — an off-road vehicle like a tractor, ATV, or UTV — RAM recommends stepping up to the larger ball size for extra stability, even if a lighter mount would technically hold the device's weight.

Diamond plate or round plate in C Size? Both carry the same heavy-duty C Size ball. This diamond plate is the compact option — 2.43″ × 1.31″ with a single 2-hole AMPS pattern (1.912″ spacing) — while RAM's round C Size plate (RAM-202U) is a wider 2.5″ disc with a 4-hole pattern that fits a broader range of cradles. Pick the diamond base when you know your holder is drilled for it or when a smaller footprint matters; pick the round plate when broad compatibility matters more.

No tools required, on purpose. RAM arms are designed to be tightened by hand only — there's no official torque spec, because the ball-and-socket joint is meant to be adjustable in the field without a wrench. If hand-tightening doesn't hold your device firmly, that's usually a sign the ball size is undersized for the device — sizing up solves it, rather than over-tightening.

Aluminum or composite — both are built for the outdoors. RAM mounts are made from marine-grade aluminum or high-strength composite, interchangeably depending on the part; both carry a lifetime warranty and similar weight ratings. Aluminum's powder-coat finish handles rough vibration and shock slightly better; composite skips the paint entirely, so it has nothing to chip, and is often preferred in high-corrosion or salt-air environments. Neither choice is "worse" — it's a trade-off between finish and environment.

Specifications

Frequently asked questions

What bolts do I need to mount this?
RAM suggests 1/4″-20 thread pitch stainless steel bolts for bolting this base down. If you're attaching a cradle to the plate instead, #8, #10, M4, or M5 screws are the common sizes — the holder usually ships with what it needs.

Does it come with mounting hardware?
No, hardware is not included — mounting surfaces vary too much for RAM to include a one-size-fits-all bolt kit. A local hardware store or your vehicle's manufacturer can confirm the right fasteners for your panel.

B or C Size for a tablet in a tractor cab?
C Size — this version — is the standard recommendation for larger tablets and handheld computers in vehicle cabs that take real vibration.

What's the overall height?
Approximately 2.25″ from the base of the plate to the top of the ball.

Does it include an arm or holder?
No — this is the diamond base plate and ball only. Add a C Size double-socket arm and a cradle drilled for the diamond pattern to complete the mount.

What's the difference vs the round C Size plate?
See the section above — this diamond plate is the smaller, lighter option with a single 2-hole pattern; the round plate (RAM-202U) is wider with a 4-hole pattern and broader cradle compatibility.