Your comma device spends most of its life stuck to your windshield. The mount holding it there matters more than most people think — heat damage, theft, and annoying cable management are all mount problems. This guide covers every option available for the comma 3, comma 3X, and comma 4.
Quick Comparison
At-a-glance pricing, compatibility, and release style.
| Mount | Devices | Type | Price | Quick-Release |
|---|---|---|---|---|
| Official comma mount | C3 / C3X / C4 | Adhesive (VHB tape) | Included | No |
| BearTech Magmount V2 | C3 / C3X | Magnetic (pogo pins) | ~$40–$52 | Yes |
| BearTech Slidemount | C3 / C3X | Physical slide | ~$39–$52 | Yes |
| BearTech Side Slidemount | C4 | Physical slide (CNC aluminum) | ~$52 | Yes |
| Janka Cross Glide Mag Mount | C3 / C3X | Magnetic | ~$100 | Yes |
| Janka C4 Magnetic Mount | C4 | Magnetic (PEI + nylon) | ~$100–$120 | Yes |
| Janka C4 Non-Magnetic Mount | C4 | CNC aluminum, mechanical latch | ~$100–$120 | Yes |
| 3D Printable (MakerWorld) | C4 | Printed plastic | Free files | Yes |
| DIY Community Mount | C3 / C3X | Printed + magnetic | ~$36 shipped | Yes |
1. Official comma Mount (Stock)
All Devices
The official comma mount comes included with every device (comma 3, 3X, and 4). It's a simple, slim adhesive bracket that sticks to your windshield with 3M VHB tape and clips the device in place. There's no quick-release — you just pull the device off and pop it back on.
Pricing: Included with device purchase
Compatibility: comma 3 / comma 3X / comma 4
Buy link: shop.comma.ai (replacement mounts available)
Installation tips from comma:
- Center the mount on the windshield, below the trim
- Leave enough room to remove the trim if needed in the future
- Ensure the top of the mount is fully visible from the driver's seat
- Clean the windshield with the included alcohol wipe before applying
- Press firmly in the center first, then the edges to prevent bubbles
Note: The stock mount is permanent adhesive — it won't come off easily on a hot day, but that also means every time you remove the device you're manually disconnecting the USB cable. If you take your device in and out frequently (to avoid heat damage or theft), a third-party quick-release mount is worth it.
2. BearTech Mounts
C3 / C3X / C4
BearTech (based in Canada) is the most established third-party mount maker in the openpilot community, with a full product line for C3/C3X and a dedicated C4 mount. Their products ship worldwide with duty prepaid.
Compatibility: comma 3 / comma 3X / comma 4 (model-specific mounts)
Pricing: Roughly ~$9 to ~$52 depending on kit and model
Buy link: shop.beartech.ca
Docs: docs.innoisle.com/beartech Discord: discord.innoisle.com Support: info@beartech.ca
BearTech Magmount V2 (C3 / C3X)
The Magmount is BearTech's magnetic quick-release mount for the comma 3 and 3X. The V2 redesign addressed all the V1 issues based on community feedback and 11+ months of 65–85°C heat testing.
What's new in V2:
- Thicker 3M VHB for curved windshields + pre-applied VHB on the windshield side
- Adhesion promoter kit included
- Device mount now mechanically fastened with 6 heat-set inserts + screws (no more glue failures)
- New magnetic shield between magnet and device (~80% field reduction) — addresses the C3X slow-fan issue
- ~50% stronger hold from a larger magnet
- Braided cable upgrade for better durability
Key specs:
- 24 pogo pins for full USB-C functionality
- 17mm slim profile
- 1/4" thread for tripod/camera mount
- Includes dummy mount (premium set) — hide your device under the dash to prevent smash-and-grab theft
Pricing: From ~$9 (windshield only) to ~$52 (full premium set)
Compatibility: comma 3 / comma 3X
Buy link: shop.beartech.ca/products/magmount-set
Note: Currently out of stock as BearTech designs Magmount V4 for the comma 4. Check back for updates.
BearTech Slidemount (C3 / C3X)
The Slidemount uses a physical sliding mechanism instead of magnets. Two-tier sliding rails give you a one-hand, no-look attach with magnets that guide you to the correct position. Only half the travel distance of traditional slide mounts, so it fits closer to the top of the windshield.
Why it exists: Some users weren't comfortable relying on magnets alone to hold a $700+ device. The Slidemount offers the convenience of quick-release with mechanical security.
Key specs:
- 14mm slim profile (0.55 inch)
- Made from ASA-CF high-temp UV-resistant material
- Built-in blade-style connector (high power delivery, secure connection)
- 1/4" screw hole on device side and windshield side
- Magnets guide placement; two-tier rails lock it in
- Use set screws to secure device side (will leave small cosmetic marks)
Warning: Slidemount does not officially support third-party comma devices. Compatible with comma C3, C3X, and C2 only.
Pricing: ~$39 (standalone set), occasionally offered at cost in community runs
Compatibility: comma 3 / comma 3X / comma 2
C4 users: A C4 Slidemount is now available — see below.
Docs: docs.innoisle.com/beartech/slidemount-c3
BearTech Side Slidemount (C4)
BearTech's dedicated comma 4 mount. The C4 has a totally different mounting slot than the C3/C3X, so this is a ground-up redesign with a CNC aluminum bracket at the core.
Why CNC aluminum? The C4's mounting slot is much smaller — plastic parts don't offer enough rigidity. The aluminum bracket guarantees a vibration-free connection.
Key features:
- 100% magnet-free — mechanical press-to-unlock latch (zero magnetic interference, no rattling)
- Zero fan interference — contoured design leaves the C4 cooling fan unobstructed
- Bi-directional sliding — attach from two different directions (useful for tight windshield angles)
- 2x the VHB tape area for strong adhesion (no waiting for VHB to cure)
- Curved mounting surface fits any windshield angle
- All-screw design with no epoxy on structural parts
- No angle wedge needed for C4
C3 upgrade paths:
- Addon A (Convert Kit): Permanently converts your old C3 Slidemount to work with C4. Note: one-way — it won't work with C3 afterward.
- Addon B (C3 Device-Side Mount for C4 base): Lets you use both C3 and C4 on the same windshield mount.
Combo deals available:
- C4 Mount + Suction Rack
- C4 Mount + CPL Filter + IR Filter
- C4 Mount + Suction Rack + CPL + IR (Ultimate Set)
Pricing: From ~$9 (windshield side only) to ~$52 (full set)
Compatibility: comma 4
Buy link: shop.beartech.ca/products/beartech-side-slidemount-c4
Docs: docs.innoisle.com/beartech/slidemount-c4 Install guide: docs.innoisle.com/beartech/slidemount-c4-installation
3. Janka / JanQuick Mounts
C3 / C3X / C4
Janka (based in China, ships worldwide) makes CNC-precision quick-release mounts for both the C3/C3X and comma 4. The name "JanQuick" appears on the store — same maker.
Compatibility: comma 3 / comma 3X / comma 4 (model-specific variants)
Pricing: Typically ~$100–$120 plus shipping depending on model
Buy link: janquick.com
Discord: discord.gg/qTy7JUAjNr Shipping: Free for orders over $30 to CN, US, UK, AU, KR, SG, JP, TH
Janka Cross Glide Mag Mount (C3 / C3X)
A horizontal magnetic quick-release mount using a transverse chute / cross-glide mechanism. Made from high-performance engineering plastics (yellow PEI, black PPS) that can withstand high temperatures.
Key features:
- CNC precision machined — smooth exterior, solid body
- High-temperature-resistant magnets (won't lose magnetism from heat)
- Customized USB wire harness with optimized routing (no tangled wires)
- Smooth positioning via sliding groove — secure fit, won't fall off
- Ships from China in ~1–2 weeks
Video demos:
Janka Comma 4 Mounts
Janka designed two distinct quick-release options for the comma 4. Both feature CNC-machined parts, a dual-locking system (mechanical/magnetic + PCB connector engagement), and clean cable routing.
Design philosophy: Stability-focused. The goal was a mount that stays solid while driving, not just one that "sticks."
Option 1: Magnetic Quick-Release (PEI + Nylon)
- Engineering plastics (PEI + nylon), smooth black surface
- High-temperature magnets with anti-misalignment design
- Magnetic strength is adjustable (remove magnets for lighter pull force)
- Very fast attach/detach — optimized for frequent removal
- Weight: ~40–65g
Video: Magnetic mount beta tester review
Option 2: Non-Magnetic Quick-Release (CNC Aluminum Alloy)
- No magnets whatsoever
- CNC-machined aluminum with sand-blasted + hard anodized surface
- Ultra-thin profile: 11mm
- Custom USB-C cable harness designed to fit the device closely
- Safety latch design
- Reserved screw holes for DIY expansion
- Can be adapted to suction cup mounts
- Compatible with the official comma mount via an adapter (no need to remove glued brackets)
Video: Non-magnetic mount beta tester review
Upgrade path: If you already own a previous Janka mount, there's an upgrade path that lets you reuse compatible parts to reduce cost.
Pricing: ~$100–$120 USD (holiday discounts available: 10% new customers, 15% returning)
Compatibility: comma 4
Buy link: janquick.com
4. 3D Printable Mounts
C3 / C3X / C4
If you have a 3D printer (or access to one), there are community-designed mounts available for free download. These are great for custom use cases — the official comma 4 windshield bracket slot makes for a solid mechanical attachment point.
Note: Use a high-temp filament like ASA or PETG for anything that'll sit in a hot car. PLA will warp.
Comma 4 Quick Disconnect with USB-C (MakerWorld)
A community-designed quick disconnect for the comma 4 that lets you connect and disconnect without manually handling the USB cable. Perfect for fast vehicle swaps or tucking the device in the glovebox.
Features:
- Mounts directly to windshield, or slides onto an existing comma 4 windshield mount
- Includes USB-C cable integration
- Full assembly instructions + required materials list included
Pricing: Free files (print/material cost varies)
Compatibility: comma 4
Download link: MakerWorld quick disconnect files
Community DIY Mechanical + Magnetic Mount (C3 / C3X)
An engineer in the community built and sells a 3D-printed ASA mount for the C3X that uses both mechanical locking and magnets for a secure, USB-integrated quick-release. The device slides from right to left; a magnet makes the USB connection and retains the lock.
Pricing: ~$36 shipped (continental USA)
Compatibility: comma 3 / comma 3X
Buy/contact: Post or DM on r/Comma_ai
Video demos:
Which Mount Should You Get?
Use the official stock mount. It's included, it works, and it's free.
Get the BearTech Slidemount (~$39). It has a strong community track record and clear documentation.
Pick BearTech Magmount V2 when available, or use the Janka Cross Glide if you need one now.
BearTech Side Slidemount C4 is the most community-tested choice. Janka C4 mounts are also solid if you prefer CNC aluminum or magnetic options.
Use the MakerWorld files for comma 4, or contact the community creator for the C3/C3X printed mount.
Angle Wedges
Both BearTech and Janka mounts support angle wedge accessories (8° and 16°) if your windshield causes the device to tilt more than 5°. Vehicles commonly needing wedges:
- Toyota Highlander (8°)
- Honda Pilot (8°)
- Ford F-150 (8°)
- Ford Maverick (8°)
- Rivian Truck & SUV (8°)
Note: Angle wedges are **not needed** for the BearTech C4 Side Slidemount.