This is a Uncle Mike's Ankle Holster, model 8820-1.
Ankle holsters can hide small and medium guns and even compact large frame autos inside the pant leg. Made of Kodra nylon with soft knot fabric for durable comfort. It has a cinch down design with hook and loop adjustment and a nylon web retention strap with reinforced thumb break.
Features:
Hook and loop adjustable
Removable calf strap
Right hand
Size 0
Fits 2' Barrel small frame 5-shot revolvers w/ hammer spur