Swapping an O3 for an O4 Air Unit Pro looks like a drop-in job on paper. Both cameras are 20 mm wide, both transmitters are roughly the same footprint, and plenty of frames are sold as "O3/O4 compatible." Then you try to bolt the new camera into the old mount and the holes are in the wrong place. This guide covers what actually differs between the O4 Pro, O4 Lite and O3, how to choose a mount for your frame, and which material to print it in.

O4 Pro vs O4 Lite vs O3: the numbers that matter for mounting

All figures below come from DJI's published specs and retailer listings. Measure your own unit with calipers before you cut or drill anything, because revisions and third-party housings vary.

DJI O4 Air Unit Pro

Camera module: about 25.55 × 20 × 23.3 mm (L × W × H), so 20 mm wide like the O3.
Camera fixing: published teardowns describe two M2 threaded holes about 16 mm apart, set back from the rear of the camera. That is a different pattern from the O3, which is why most O3 side-plate mounts don't carry over.
Transmitter: about 33.5 × 33.5 × 13 mm, with M2 holes at 20 × 20 and 25.5 × 25.5 mm.
Weight: about 32 g with the camera, plus two antennas of about 2.1 g each. Two antennas means two antenna mounts, or one dual mount.
Lens: 1/1.3-inch sensor with a 155° field of view. A wide lens sees more of the frame, so mount tilt and the position of the front standoffs matter more than they did with narrower cameras.

DJI O4 Air Unit (often called O4 Lite)

Camera module: about 13.4 × 12.4 × 16.5 mm. It is a micro-class camera, nowhere near 20 mm wide.
Transmitter: about 30 × 30 × 6 mm and around 5 g, with a single antenna.
Typical use: whoops, toothpicks and 2–3.5 inch builds where every gram counts. Many frames use a 14 mm camera slot, so you need an adapter or a dedicated canopy.

DJI O3 Air Unit

Camera module: about 21.2 × 20 × 19.5 mm. Same width as the O4 Pro, shorter body.
Transmitter: about 32.5 × 30.5 × 14.5 mm and about 36 g with the camera, one antenna.
Status: several retailers now list it as discontinued, but there are a lot of O3 builds still flying, and the camera module is still sold as a spare.

The short version: an O4 Pro will usually fit in the space an O3 occupied, but it needs its own camera mount and a second antenna position. An O4 Lite needs a different mount entirely.

Frame-by-frame: picking the right O4 Pro mount

Printed mounts are frame-specific because the standoff spacing, standoff diameter and top-plate shape are frame-specific. Start by identifying three things on your frame: the distance between the front standoffs, the standoff diameter (usually 5 mm or 6 mm on 5-inch frames), and whether the camera sits between side plates or in a printed pod.

GEPRC Mark4 (5-inch)

The Mark4 and its many clones are still among the most common 5-inch freestyle frames. For an O4 Pro build you need a rear mount that holds both antennas. Our Mark4 O4 Pro antenna mount does that (no GPS slot). If you want GPS, receiver and antennas in one go, the GEPRC Mark4 O4 Pro parts kit bundles the antenna mount with a GPS mount, receiver holder and more.

ImpulseRC Apex 5-inch and clones

The Apex geometry is copied by many budget frames. The OG Apex O4 Pro camera mount holds the camera between the front standoffs, and the OG Apex O4 Pro soft-mount cage isolates the transmitter from vibration. If your clone uses different standoff spacing, measure first.

iFlight frames: Chimera7 Pro and Mach R5

Long-range 7-inch builds benefit from the O4 Pro's range and image quality. The O4 cam/antenna mount for the Chimera7 Pro handles both jobs in one part. For the Mach R5, the O4 Pro camera mount for the Mach R5 is drawn for 28 mm stud spacing and 5 mm standoffs.

Quadmula Siren F5 and F5 Mini

These frames have a distinctive rear end, so generic antenna tubes don't sit well. Use the Quadmula F5 antenna mounts for O4 Pro.

Frames without a dedicated mount

If your frame isn't listed, a universal pod is usually the fastest path. The O4 Pro air unit camera pod and the O4 Pro hot-swap pod wrap the camera so you can move it between quads. Browse the full DJI O4 Pro mounts collection for everything we list.

O4 Lite and O3 builds

For O4 Lite whoops and toothpicks, see the O4 Lite mounts collection, which includes a 14 mm camera mount, a canopy and the PicklePod. Still flying O3? The O3 mounts collection covers frame-specific mounts, such as the Mark5 O3 mount, plus antenna caps.

TPU vs PETG vs nylon-CF for camera and antenna mounts

Material choice matters as much as geometry. A mount that is perfectly sized but in the wrong plastic will crack on the first cartwheel or sag on a hot day.

TPU 95A: the default for anything that hits the ground

TPU is a flexible, rubber-like plastic. It bends in a crash and springs back, which protects the camera and keeps the mount from snapping. Nearly every printed camera mount and antenna holder in FPV is TPU for that reason. The trade-off is that it isn't stiff, so a TPU mount can let the camera tilt slightly under hard throttle. On a well-designed mount that tilt is negligible.

PETG: good for prototypes and protected parts

PETG is stiffer and cheaper but much more brittle in an impact. It is fine for a test fit, or for parts tucked inside the frame such as a receiver holder. We don't recommend it for front-facing camera mounts on a freestyle quad.

Carbon-fiber nylon (PA6-CF, PAHT-CF): stiff brackets

Carbon-fiber nylon is light, very stiff and handles heat well. It makes sense for structural brackets, long-range antenna masts or anything that must hold a precise angle. It is not a crash absorber. If the part is meant to flex, use TPU. For more detail, read our TPU vs carbon-fiber nylon guide or the materials guide.

Install tips that save a reprint

Test-fit the camera in the mount before you put the mount on the frame. TPU is snug by design and loosens slightly after the first install.
Don't overtighten M2 screws into the camera. The holes are threaded metal in a small housing, and stripping one is expensive.
Route the coax before closing the frame. The O4 Pro coax is short, so plan the path from camera to transmitter.
Set the camera angle for how you fly, then check the props aren't in view at full tilt. The 155° lens sees more than the O3 did.
Keep the antennas apart and pointing in different directions. That is the point of the dual-antenna design.

Can't find your frame?

If your frame or camera combo isn't in the catalog, upload an STL, STEP or 3MF file to the instant quote page. The quote is based on a real print simulation, not a guess. Every catalog part is covered by our fit guarantee: if it doesn't fit the listed frame, send a photo within 30 days and we reprint it free. Standard turnaround is 2–3 business days, and small parts ship by USPS Ground Advantage at the actual carrier rate.

FAQ

Will my O3 camera mount fit the O4 Pro?

Usually not. The O4 Pro camera is the same 20 mm width, but it is longer and its fixing holes are in a different position, so most O3 side-plate mounts won't line up. You also need a place for the second antenna.

Can I put an O4 Lite in a 5-inch frame?

You can, but the O4 Lite camera is roughly 12 mm wide and needs an adapter or pod to sit in a 19–20 mm camera bay. Most pilots use it on whoops and small builds where its weight saving matters.

What material should my O4 Pro mount be printed in?

TPU 95A for camera and antenna mounts that take crashes. Use carbon-fiber nylon only for stiff structural brackets that shouldn't flex.

DJI O4 Pro mounts: which one fits your FPV frame