This is a Advanced Technology Grip, model SRG0200.
The Advanced Technology Int. Shotforce RPG is a 12ga and 20ga (proud fit) shotgun rear AR-style pistol grip with a slim ergonomic design for comfort. It fits Maverick 88 12ga & 20ga (proud fit)" Mossberg 500/535/590/835 12ga & 20ga (proud fit)" Remington 870 12ga & 20ga (proud fit)" American Tactical MB3" and Winchester 1200/1300 12ga & 20ga (proud fit). The textured grip increases control and accuracy. It is easy to install and includes adapters for all supported models and all mounting hardware. Made in the USA.
Features:
AR-Style rear pistol grip
Top-mounted sling loop
DuPont® Extreme Temperature Glass Reinforced Polymer