As per Manufacturer's site:
The Magpul Enhanced Rubber Butt-Pad, 0.70" is an optional replacement butt pad for the CTR® and MOE® Mil-Spec stocks as well as all STR®, ACS-L™, ACS™ and UBR® stocks. It is designed for enhanced shoulder purchase as well as offering slightly improved recoil reduction with its thicker, vented construction. The Enhanced Rubber Butt-Pad can also be installed on Commercial-Spec MOE/CTR stocks, but may prohibit use of fully collapsed position due the extended, slanted back of most commercial-spec receiver extensions.
All mounting hardware included.