Extremely rugged, one piece free float design and construction Featuring seven sides of M-LOK(TM) compatible slots MI-SP12M Rifle - 12.625" model weighs 12.8 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