That’s not their product, the new stuff is. AAC was sold many many years ago.I contacted AAC and they were useless. I have the original AAC Owners manual that says it’s designed for the USP and Glock 21 without any sort of adapter and they argued I was wrong. It works perfect with the USP, I wouldn’t buy an Advanced Armament product again. You can tell a lot about a company when you have an issue and how they stand behind their product; very poor customer service.