A 1.3 inch I.D. will accommodate most low-profile gas blocks. Some interference with clamp-on style low profile gas blocks is possible. MLok slots at the 3, 6 and 9 positions are manufactured to MAGPUL standards. This ensures proper fitment with any MAGPUL certified accessories. Every AR10 & AR15 Cornerstone handguard comes with a pre-heat treated, 2 inch length 4140 steel barrel nut. This ensures rigid, rock-solid accessory mounting. The barrel nut has been nitrided, not phosphated. Mounting instructions and hardware are included with every AR10 & AR15 handguard.
Specifications:

Type
Firearm Type
Firearm Model
Material	6061-T6 Aluminum
Finish	Anodized
Features
Adjustment Type
Positions
Length of Pull
Rails	Picatinny
Texture Type
Swivel Studs
Free Floating	Yes
Grip Type
Tube Included
Capacity