The biggest leap in silencer technology and design in a long time. HUXWRX silencers feature a patented Flow-Through design that creates channels to move gases throughout the silencer, creating tremendous surface area and drag that slows gases down and expels them out the front. This dramatically reduces back pressure sent into the rifle and ultimately into your face. The FLOW 556k is DMLS printed in 17-4 Stainless and delivers superior toxic fume mitigation, flash reduction, sound reduction, recoil reduction, accuracy, and repeatability. Full-auto rated, compatible on 5.56, 17 HMR, and 5.7 platforms. Has passed the SOCOM Reliability Stress Test Firing Schedule a minimum of 6 times. Compatible with Muzzle Brake-QD 556 and Flash Hider-QD 556. Note: If this product is reflected as in-stock it means it's either physically in-stock or allocated and available (serial number is assigned) at my distributor