Shopping > AR-15 Parts > Tactical Sights, Gas Blocks, Sight ToolsClick for larger image Single Rail Gas Block Price: $0.00 Select Barrel Diameter .750 Barrel Dia. GB-SR7 (+$45.95) .936 Barrel Dia. GB-SR9 (+$45.95) 1925:+:45.95,1926:+:45.95 Quantity: Single Rail Picatinny Rail on top of Gas Block. (.750 Diameter) or (.936 Diameter) Select Barrel Size Below
 "Single Rail Gas Block")