This is a Keystone Sporting Arms 1 Piece Base, model 031.
The rail utilizes a standard weaver style or 3/8" dovetail mounting system. This scope rail is the same one that now comes standard with all Crickett Gen. 2 youth rifles. When your young marksman is ready to upgrade" pair it up with the Crickett Scope and open a whole new experience of shooting fun.
Also compatible with Keystone Sporting Arms' Chipmunk line of rifles