Extremely rugged, one piece free float design and construction Features seven sides of M-LOK compatible slots Inside Diameter is 1.75" Outside Diameter is 2.0" High qualtity MIL-STD 1913 top rail T-Marked for accessory location One five slot M-LOK polymer rail section included Barrel nut wrench included Constructed from 6061 aluminum and hard coat anodized for a life of service 100& Made in the USA