{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "ram-mount-ball-sizes",
 "name": "RAM-style mount ball sizes: A 0.56, B 1, C 1.5, D 2.25 and E 3.38 in",
 "kind": "standard",
 "category": "Everyday mounts",
 "group": "Phone & camera mounts",
 "year": null,
 "question": "What size is a RAM mount ball?",
 "tags": [
  "ram mount",
  "ball mount",
  "phone mount",
  "tablet mount",
  "mount",
  "1 inch ball"
 ],
 "aliases": [
  "ram mount ball size",
  "ram b ball diameter",
  "ram 1 inch ball",
  "ram c size ball",
  "ram ball step",
  "ram ball stl",
  "1 inch ball mount"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 5,
 "url": "https://xemstudio.com/objects/ram-mount-ball-sizes/",
 "sheet_txt": "https://xemstudio.com/objects/ram-mount-ball-sizes/sheet.txt",
 "sheet": {
  "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",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "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."
  ],
  "table": {
   "columns": [
    "size",
    "ball (in)",
    "ball (mm)",
    "used for (RAM)"
   ],
   "rows": [
    [
     "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"
    ]
   ]
  }
 },
 "sheet_text": "RAM-style mount ball sizes: A 0.56, B 1, C 1.5, D 2.25 and E 3.38 in — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ram-mount-ball-sizes/  (CC BY 4.0)\nBasis: 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\nCatalog version: 2026-10-20\n\nSizes: see table below\n- 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.\n- 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.\n- 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.\n\nsize  ball (in)  ball (mm)  used for (RAM)\nA  0.56  14.224  action cameras and other very light gear\nB  1  25.400  phones, GPS units, small tablets\nC  1.5  38.100  large tablets, fish finders, rough rides\nD  2.25  57.150  rugged tablets, laptops, heavy equipment\nE  3.38  85.852  large displays, aviation and industrial use\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- 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) — web — manufacturer page [verify license at link] — https://rammount.com/products/ram-d-202u\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 5 parts): https://xemstudio.com/files/hardware/ram-mount-ball-sizes/index.json\nAPI: https://xemstudio.com/api/geometry?object=ram-mount-ball-sizes\n",
 "sources": [
  {
   "publisher": "RAM Mounts",
   "title": "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)",
   "url": "https://rammount.com/products/ram-d-202u",
   "formats": [
    "web"
   ],
   "license": "manufacturer page",
   "license_verified": false,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "phone-mount-ball-17mm",
  "handlebar-clamp-rings",
  "camera-thread-bosses-1-4-20"
 ],
 "fits": [
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "handlebar-clamp-rings",
     "why": "a ball unioned onto a bar clamp"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "phone-mount-ball-17mm",
     "why": "17 mm ball of clip-on phone holders"
    }
   ]
  }
 ],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "ball",
   "exact": "Ø14.224 / 25.4 / 38.1 / 57.15 / 85.852 (A–E)",
   "mates": "RAM-style double-socket arm of the same size",
   "fit": "socket",
   "files": "ram-ball-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "What size is a RAM B ball?",
   "a": "1 in (25.4 mm). A is 0.56 in, C 1.5 in, D 2.25 in, E 3.38 in."
  },
  {
   "q": "Do RAM B and C parts fit each other?",
   "a": "Not directly: a B arm clamps 1 in balls, a C arm 1.5 in balls."
  },
  {
   "q": "Is a RAM B ball the same as a phone holder ball?",
   "a": "No: clip-on phone holders use a 17 mm ball; RAM B is 25.4 mm."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "ram-ball-a-0.56in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "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",
   "note": "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)"
  },
  {
   "file": "ram-ball-b-1in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "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",
   "note": "RAM-style B size ball: Ø1 in = Ø25.400 mm sphere (the ball only; the base or arm it sits on differs per part)"
  },
  {
   "file": "ram-ball-c-1.5in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "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",
   "note": "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)"
  },
  {
   "file": "ram-ball-d-2.25in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "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",
   "note": "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)"
  },
  {
   "file": "ram-ball-e-3.38in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "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",
   "note": "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)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ram-mount-ball-sizes/index.md"
}