The SilencerCo Gas Defeating Charging Handle (GDCH) is a novel AR-15 charging handle which utilizes proprietary design features to provide the most effective gas blow back mitigating properties available on the market today. Features : Utilized on both 5.56 NATO and .300BLK chambered AR-15 platforms O-ring seal to prevent gases from escaping, Ambidextrous and oversized handles Manufactured with 7075 aluminum