This is a Russian made adjustable but pad for polymerstocks (can also be installed on a triangle stock with different screws). It is made out of a reinforced polymer. It’s adjustable in thickness by adding or removing inserts.
The cheek rest is secured to the stock with 2 screws(included). Pictured stock, rifle and adjustable cheek rest (available separately) are not included. All items pictured in photo #1 are included in the kit. Does not interfere with locking the stock in the closed position.