RAM Stubby Cup Holder Base with Diamond (AMPS) Plate
A compact starter base that drops into an existing vehicle cup holder and turns it into a mounting point -- via a short B Size arm ending in a standard 2-hole diamond (AMPS) plate, ready for a phone or tablet holder with a matching pattern.
Why start from the cup holder
Not every vehicle has a rail, roll bar, or flat dash panel that a mount can attach to -- but almost every vehicle has a cup holder. The RAM Stubby wedges spring-loaded fingers against the inside walls of a cup holder from 2.57" to 3.5" in diameter, providing a genuinely stable base without touching the dashboard, windshield, or any factory trim. Unlike RAM-B-132-400U and RAM-B-132SU on this page, this SKU is not itself a drink holder -- it repurposes an existing one as a mounting point, ending in a diamond AMPS plate rather than a device cradle, so you can bolt on whichever RAM holder matches your phone, tablet, or camera (sold separately, or already in your kit if you are combining mounts).
Features
- Spring-loaded wedge base fits cup holders from 2.57" to 3.5" inside diameter, no tools required
- Short B Size double socket arm connects the base to a standard 2-hole diamond (AMPS) plate
- Also available with a round AMPS plate instead of diamond, for holders using that pattern
- High-strength composite construction
How RAM's modular system works
Every RAM mount is built from up to three parts that click together. A base clamps, bolts, or straps onto the vehicle -- a dash, a windshield, a cup holder, or a rail. An arm connects two RAM balls together and can be locked at any angle, so once mounted you can tilt, rotate, and reposition the device freely, then lock it firmly in place by hand. A cradle or holder grips the specific device -- phone, tablet, or drink.
Not every product includes all three parts -- some are just the base, some bundle a holder, some are a complete kit. This page says plainly which parts are included with this particular SKU, so you know exactly what you are getting and what, if anything, you would 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. This base ends in a diamond AMPS plate, not a ball -- so it is compatible with any RAM holder or cradle that has the matching 2-hole diamond pattern on its back, in addition to the B Size arm that connects the plate to the cup-holder wedge. B Size (part numbers starting RAM-B-...) is RAM's most common size, standard duty -- what RAM recommends for phones, GPS units, and light tablets in normal use. C Size (plain RAM-... part numbers, no letter prefix) is heavy duty, used for larger tablets and anything mounted somewhere that gets a lot of vibration or shock. D and E Size are reserved for large monitors and specialist equipment.
Rule of thumb: if the mount will live somewhere frequently jostled or vibrated -- an off-road vehicle, a gravel road at speed -- RAM recommends stepping up to a larger ball size for extra stability, even if a lighter mount would technically hold the device's weight.
No tools required, on purpose
RAM arms are designed to be tightened by hand only -- there is no official torque spec, because the ball-and-socket joint is meant to be adjustable in the field without a wrench. If hand-tightening does not hold your device firmly, that is usually a sign the ball size is undersized for the device -- sizing up solves it, rather than over-tightening.
Aluminum or composite -- both built for the outdoors
RAM mounts are made from marine-grade aluminum or high-strength composite, depending on the product; both carry a lifetime warranty and similar weight ratings. Aluminum's powder-coat finish handles rough vibration and shock slightly better; composite has no paint to chip and is often preferred in high-corrosion or salt-air environments. Neither choice is worse -- it is a trade-off between finish and environment.
Specifications
| Ball size | B Size (1") |
| Arm length | Medium (socket-to-socket: 3") |
| Cup holder fit | 2.57" - 3.5" inside diameter (approx. 65 - 89 mm) |
| Overall height | 8.7" (approx. 221 mm) |
| Mounting plate | 2-hole diamond AMPS, 1.912" hole spacing, plate 2.43" x 1.31" |
| Weight capacity, standard use | 2 lbs (approx. 0.9 kg) |
| Weight capacity, heavy-duty use | 1 lb (approx. 0.45 kg) |
| Materials | High-strength composite |
| Packaging | Poly bag |
| Weight | 1.48 lb (approx. 0.67 kg) |
Frequently asked questions
Does this include a phone or tablet holder?
No. This SKU is the cup-holder base, arm, and diamond AMPS plate only -- it is a mounting point, not a complete kit. Pair it with any RAM cradle or holder that has a matching 2-hole diamond pattern, such as an X-Grip phone holder or a tablet cradle.
How firmly does it grip the cup holder, and does it damage it?
The spring-loaded fingers press outward against the cup holder's inner walls -- firm enough to keep an arm and holder stable while driving, without adhesive or modification, and it lifts back out cleanly.
What device sizes does this support?
That depends entirely on which diamond-pattern cradle you pair it with -- this base itself only determines the cup-holder fit (2.57"-3.5") and the B Size weight rating (2 lbs standard use).
Is drilling required?
No. The wedge base is entirely tool-free in the cup holder, and any holder you bolt to the diamond plate simply screws onto the plate itself.
Can I get a round plate instead of diamond?
Yes -- RAM offers this same Stubby base with a round AMPS plate as an alternate option, for holders that use the round pattern instead.