The B.E. Meyers 249F Flash Hider has proven time and time again to be one of the most effective flash hiders available. According to a formal US Army evaluation, the 249F eliminates 96% of all visible muzzle flash and was awarded the highest score during testing. This prevents momentary night blindness and eliminates flash distortion of night vision devices, allowing you to effectively maintain target awareness throughout an engagement. The 249F fits 5.56mm rifles with 1/2-28 muzzle threads. The flash hider weighs in at 2.5oz and has dimensions of 2.75"" x .865"". NSN: 1005-01-526-3464 Mfg: B.E. Meyers & Co., Inc.