(R)ecoil (R)eduction (D)evice (4) ports (C)ompensator (30) 5/8x24 threads - rated for 30 cal (S)houlder (KM) KeyMo The best of both worlds! Their super effective RRD4-4C muzzle brake comp with KEYMO suppressor mount! Specifications: Threads: 5/8x24 Length: 2.82" long Material: 17-4ph Stainless Weight: 3.84oz This is a licensed product through Dead Air Silencers. JMac Customs is NOT responsible for improper installation of this muzzle device or any damage to the suppressor using this device. We recommend this be professionally installed and checked to ensure alignment.