This is a Kydex Clip that attaches directly to your belt up to 1.75in. That holds your Weapon by the Handle.
It can be set to swivel in place, free rotation, or locked in place by a Chicago screw, and can be changed between the different set ups by moving the screw.
Do not remove the center screw unless you want to take it apart to attach to whatever you want as it is lock tight in place.