UTG Pro AR-15 Low-pro Quad-rail Gas Block for .75in Barrel Black. 75in Barrel is perfect for any modified weapon system. This picatinny rail low profile gas block attachment from UTG Pro is perfect for mounting flip-up iron sights tactical flashlights and tactical laser lights. This profile replaces A2 front sight and provides 4 picatinny rails. Use this UTG Pro Model 4/15 Low Profile Quad Rail Gas Block Rail System with an M4/AR15 rifle and give yourself the tactical advantage. Specifications for UTG Pro AR15 Low Pro Quad-rail Gas Block for .75in Barrel: Manufacturer: UTG Pro Color: Black Fabric/Material: Aircraft Grade Aluminum Gun Make: AR Platform Gun Model: AR-15 Condition: New Hand: Ambidextrous Country of Origin: USA Finish: Matte Features of UTG Pro Model 4/15 Low Profile Quad Rail Gas Block: Low Profile Fits .75" regular barrel and standard gas tube Precision machined from aircraft grade aluminum with tight tolerances Top rail lower than flat top by .28" Comes with a gas tube roll pin and locking screw Package Contents: UTG Pro AR15 Low Pro Quad-rail Gas Block for .75in Barrel What firearm models does the manufacturer say UTG Pro AR15 Low Pro Quad-rail Gas Block for .75in Barrel is compatible with? The manufacturer says that UTG Pro AR15 Low Pro Quad-rail Gas Block for .75in Barrel is compatible with AR-15UTG Pro MTU012: AR-15 Low-pro Quad-rail Gas Block for .75in Barrel Black