This is a Luth-AR Grip known as the Chubby, model PG-01.
Luth-AR's Chubby Grip is designed with shooter ergonomics in mind. The full palm swell fills the hand" providing a consistent and rapid grip" properly positioned to promote accurate and repeatable shots on target. The thumb rest and palm shelf work together to lock the hand in place shot after shot" while the raised trigger finger surface" forces the finger into the proper curved position for better trigger control and comfort. Available Right Hand only. Includes screw and washer.
Features:
A hand fitted grip that offers a natural hand-in-glove feel
A natural extension between hand and rifle
Textured for a non-slip grip