The thread insert on the Logitech C920 that allows it to mount to tripods and other standard webcam mounts that use the standard 1/4-20 threading can sometimes fall out.

This is a simple replacement if your C920 has a missing thread insert. It's sized so that it should be a basic friction fit into the camera and I've personally not encountered any issues with that.

It's possible this also fits other Logitech webcams as many of them use very similar mounting hardware, but I've only tested with the C920 specifically.