# RAM-style mount ball sizes: A 0.56, B 1, C 1.5, D 2.25 and E 3.38 in

> What size is a RAM mount ball?

- Category: Everyday mounts › Phone & camera mounts
- Kind: Standard part
- Basis: RAM Mounts: the letter after RAM names the ball size, A 0.56 in, B 1 in, C 1.5 in, D 2.25 in, E 3.38 in
- Page: https://xemstudio.com/objects/ram-mount-ball-sizes/ · JSON: https://xemstudio.com/api/geometry?object=ram-mount-ball-sizes · Plain text: https://xemstudio.com/objects/ram-mount-ball-sizes/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- RAM mounts join with a rubber ball on the base and a double-socket arm that clamps two balls. The letter in a RAM part number is the ball size; C-size parts carry no letter.
- Files: each ball as a sphere at the published diameter. The ball is the interface; the neck and base under it differ from part to part and are not drawn. Union a ball onto your own base to mate with a RAM arm of that size.
- Ball diameters are given in inches by RAM; the mm figures are the exact conversions. The rubber ball is drawn as a rigid sphere at its published size.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| ball | Ø14.224 / 25.4 / 38.1 / 57.15 / 85.852 (A–E) | RAM-style double-socket arm of the same size | socket | ram-ball-* |

## Sizes

| size | ball (in) | ball (mm) | used for (RAM) |
|---|---|---|---|
| A | 0.56 | 14.224 | action cameras and other very light gear |
| B | 1 | 25.400 | phones, GPS units, small tablets |
| C | 1.5 | 38.100 | large tablets, fish finders, rough rides |
| D | 2.25 | 57.150 | rugged tablets, laptops, heavy equipment |
| E | 3.38 | 85.852 | large displays, aviation and industrial use |

## Where the files are

- RAM Mounts: [Ball sizes by letter: A 0.56 in, B 1 in, C 1.5 in, D 2.25 in, E 3.38 in (RAM-D-202U page)](https://rammount.com/products/ram-d-202u) — web — manufacturer page (verify at link)

## Free STEP/STL (5 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/ram-mount-ball-sizes/index.json

- ram-ball-a-0.56in: [STEP](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-a-0.56in.step) · [STL](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-a-0.56in.stl) — RAM-style A size ball: Ø0.56 in = Ø14.224 mm sphere (the ball only; the base or arm it sits on differs per part)
- ram-ball-b-1in: [STEP](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-b-1in.step) · [STL](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-b-1in.stl) — RAM-style B size ball: Ø1 in = Ø25.400 mm sphere (the ball only; the base or arm it sits on differs per part)
- ram-ball-c-1.5in: [STEP](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-c-1.5in.step) · [STL](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-c-1.5in.stl) — RAM-style C size ball: Ø1.5 in = Ø38.100 mm sphere (the ball only; the base or arm it sits on differs per part)
- ram-ball-d-2.25in: [STEP](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-d-2.25in.step) · [STL](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-d-2.25in.stl) — RAM-style D size ball: Ø2.25 in = Ø57.150 mm sphere (the ball only; the base or arm it sits on differs per part)
- ram-ball-e-3.38in: [STEP](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-e-3.38in.step) · [STL](https://xemstudio.com/files/hardware/ram-mount-ball-sizes/ram-ball-e-3.38in.stl) — RAM-style E size ball: Ø3.38 in = Ø85.852 mm sphere (the ball only; the base or arm it sits on differs per part)

## How it fits

### Connects to
- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/): a ball unioned onto a bar clamp

### Alternatives
- [17 mm ball joint for phone mounts (ball stud)](https://xemstudio.com/objects/phone-mount-ball-17mm/): 17 mm ball of clip-on phone holders

## Questions

**What size is a RAM B ball?**

1 in (25.4 mm). A is 0.56 in, C 1.5 in, D 2.25 in, E 3.38 in.

**Do RAM B and C parts fit each other?**

Not directly: a B arm clamps 1 in balls, a C arm 1.5 in balls.

**Is a RAM B ball the same as a phone holder ball?**

No: clip-on phone holders use a 17 mm ball; RAM B is 25.4 mm.

## Fits with

- [17 mm ball joint for phone mounts (ball stud)](https://xemstudio.com/objects/phone-mount-ball-17mm/)
- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/)
- [Camera tripod thread bosses: 1/4-20 UNC and 3/8-16 UNC](https://xemstudio.com/objects/camera-thread-bosses-1-4-20/)