Extremely rugged one piece free float design and construction – Featuring seven sides of M-LOK(TM) compatible slots – MI-SP7M Carbine – 7.25 model weighs 9.0 ounces with barrel nut – Inside diameter 1.75 inch outside diameter 2.0 inch 1.95 inch over mounting flats – High quality MIL-STD 1913 top rail T-marked for accessory location – One five slot Magpul(R) M-LOK(TM) polymer rail section included – Barrel nut wrench included – Construction from 6061 aluminum hard coat anodized for a lifetime of service – MI Lifetime Warranty – 100% Made in America – Keeps America Working – US Patent Number USD788871