Midwest Industries SP Series, Handguard, Fits AR-15 Rifles, 10.5, M-LOK, Black MI-SP10M The Midwest Industries SP Series M-LOK Handguard is a rugged one-piece design constructed of 6061 aluminum with a hard coat anodized finish. It features a full length Picatinny top rail and M-LOK mounting slots on 7 flats along its length. The SP Series is designed to provide room for a sound suppressor" with an inside diameter of 1.75" and outside diameter of 2". It comes with one 5-slot M-LOK accessory rail and all mounting hardware. Midwest Industries is a proven leader in the firearm industry. Made in the USA" focusing on the small details to make your rifle platform better.