Holosun Technologies 407/507K Adapter, Black, Fits Glock 19/17/45 MOS, Will Not Fit 43X/48 MOS KPLT-MOS9MM The Holosun 407/507K Adapter for GLOCK MOS is a rugged and reliable mount, perfect for use with law enforcement, the military, and the everyday shooter. CNC machined with 6061 aircraft aluminum with a Type III Hard Anodized Finish, this mount is designed to withstand even the hardest-hitting recoil as well as rough use and abuse in virtually any tactical environment.