Al

These look very similar to the mounts on my K gun except mine is a bridge type set up. Basically the round knurled wheel on the rear base is rotated. This action retracts a small claw upward into the base and off the left hand dovetail. From there you just swing the whole thing to the right until its at 90 degrees and lift it off at the front of the rib.

Mine is called a "G9 Plus" and I think its by EAW.

Cheers.

GG