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