The Madbull Barrett REC7 Gas Block Kit come with an outer barrel, gas black, and adjustable short-stroke piston.
It can be used with most free float rail systems as well as FSP rail systems. What you get with this upgrade is an awesome looking system for your M4 and easy installation. It comes in Matte Black and is a stunning replica of the original designed and licensed by Barrett. If you want the best look and quality performance you know Madbull has you covered.