DJI Osmo Pocket 3 Expansion Adapter
Nothing else in the DJI mounting range reaches this camera without it, it is in neither box, and DJI names it as the condition on its own backpack mount listing.
Install note
Opened and read back on 2026-07-26: "DJI Osmo Pocket 3 Expansion Adapter", DJI-authored bullets, in stock. The listing carries the same sentence DJI publishes on its own store: "The Expansion Adapter can expand to fit a cold shoe and an action camera port. With this adapter, Osmo Pocket 3 can be compatible with most Osmo Action accessories (such as the Osmo Backpack Strap Mount)." Note what that sentence does not say. It does not say the adapter adds a 1/4 inch thread, and no DJI document does. What it buys you is the Osmo Action two-prong mount ecosystem, and most of those accessories end in their own thread. DJI also documents a real fitting caveat in its FAQ: you align the adapter with the curved edge of the joystick base and must "Ensure the proper installation position while also allowing screen rotation before fastening the adapter buckle", which means it can be fitted in a position that stops the screen turning.