Answer: The thread size of the inserts into which the rubber feet are screwed is M4. The other insert found on the bottom of the cabinet is for attaching the 3000WB wall bracket, this is an M8 insert.
Attached are the instructions for the setup, use and care of your Q Acoustics Q B12 Active Subwoofer. Note: Unauthorised redistribution, publication online or otherwise of the attached documentation and images are protected under copyright.