The Rubber Butt-Pad 0.30″ comes standard with the CTR and MOE Mil-Spec Carbine models as well as all STR ACS-L ACS and UBRstocks and utilizes a firm rubber that is designed for enhanced shoulder purchase and improved impact/drop mitigation. May also be installed on Commercial-Spec MOE/CTR stocks but may prohibit use of fully collapsed position. All mounting hardware included. Made in USA. *Note- Not compatible with MOE Fixed Carbine Stock.