Effective muzzle brake with integrated HexaLug interface. Compatible with all suppressors featuring our HexaLug quick attach mounting system. Due to the one-way compatibility of HexaLug it is possible to install a suppressor of a larger caliber, too. This allows the installation of a 7.62 mm suppressor on a 5.56 mm muzzle brake. On rifles that are primarily or exclusively used with a suppressor, a muzzle brake should be used instead of a flash hider. The ports of the muzzle brake redirect high-pressure gas towards the side and therefore prolong the life of the suppressor. Please note the increased intensity of the muzzle blast affecting bystanders next to the shooter if the rifle is used without a suppressor. Thread Size Guide: 1/2″ – 28 UNEF Standard thread on almost all American made rifles chambered in a 5.56 mm caliber M13 x 1L (Steyr AUG) Specific variant for Steyr AUG M14 x 1 Fits all variants of the Czech made vz.58, occasionally found on hunting rifles. Early Haenel CR223 rifles used the M14 x 1, too. M14 x 1L Fits some of the rarer Romanian AK variants chambered in 5.45 x 39 mm, the more common Norinco Type 84S and probably others M15 x 1 Fits Haenel CR223 and many other rifles. Not compatible with HK MR223, HK 33, etc. M15 x 1 HK Specifically designed to cover the cylindrical section between the muzzle thread and the shoulder on an HK MR223. Do not use this with rifles made by Haenel.