This is a Seekins Precision Stock known as the ProComp 10x, model 0011810001.
Featuring an adjustable cheek rest and recoil pad" the ProComp 10x is a precision rifle stock designed for all AR platforms. Cheek piece adjustments are accomplished by utilizing their dual push button and clamping system which securely locks the cheek piece to the shooters desired height. The recoil pad is adjusted via spacer system and each stock comes with two 1/4 spacers. The 10x is intended to act as a stable link between shooter and rifle to ensure that confidence is paired with each shot.
Features:
Black finish
Usable on all Mil-Spec AR15 & AR10 platform rifles
Mounts to rifle-length receiver extension tube
Anti-rotation QD sling swivel mounts