This is a Sig Sauer known as the Grip Module, model GRIP-MOD-C-943-SM-BLK.
Install your P320/P250 firing control unit into this Grip Module Assembly to convert to a P320 or P250 compact chambered in 9mm" .357 SIG" .40AUTO. Requires the 9mm" .357 SIG and .40AUTO slide and barrel. Available in three sizes (small" medium" large) and three colors (Black" ODG" FDE).
Features:
Black finish
Requires the 9mm .357 SIG and .40AUTO slide and barrel;Size small