Advanced Armament Corp (AAC) makes the AAC piston for use with their pistol suppressors, such as the Ti-RANT series. This part lets the suppressor work properly with the recoil action of semi-auto pistols. It fits AAC suppressors and threaded pistol barrels in various thread pitches, as well as handguns in 9mm, .40 S&W, and .45 ACP. You can swap the AAC piston for different thread types, so it works across many pistol platforms.