Ruger American Rifle Gen II Length-of-Pull Spacer KitThe Ruger American Rifle Generation II stock incorporates spacers that adjust the stock's length of pull (LOP). The correct length of pull improves the rifle's comfort and feel and improve accuracy by making shoulder placement and sight acquisition faster and more consistent. The rifle ships with a 13. 75'' length of pull spacer installed. The spacers in this kit allow additional adjustment to the rifle's LOP. The spacers included in the kit provide a