Accessory Mounting Block Kit Arri enables attachment of up to 3 kg of Arri‑fitting accessories to Miller ArtX, CX and Compass heads, using standard 1/4‑20 and 3/8‑16 threads. The compact block provides a rigid mounting point for items such as external viewfinders and other Arri‑compatible add‑ons, without altering head balance. It weighs 0.13 kg and expands rig versatility while preserving quick setup and compatibility with Miller’s accessory ecosystem.