French kydex bender, PYRENEES.TAC, is doing some very interesting things with kydex knife sheaths including this clever retention strap.
The shock cord strap wraps over the guard of the knife to act as a secondary retention aid. The sheath has a small stud that the strap hooks onto via a pull-tab that is molded to fit the stud. This is a very clever way to use standard, pre-existing hardware to create something new.
You can check out PYRENEES.TAC on their Facebook page.