Truth biscuit keeper used on Encore Multipoint Locking System.
used by Shelter windows, Jeld-Wen and others

Measurements:
Tab-to-hook projection: 1 inch
Tab-to-curve-apex: 13/16 inch
Screw hole length: 1-1/4 inches

Related Parts:
556009 - Encore Multipoint Lock Assembly, Handle and Escutcheon

Priced and sold each.