This model fits: AR15s with the Mid-Length Gas System. This replaces standard Mid-Length handguards. Solid fit, top rail is at receiver height and you have M-LOK slots along each sides and the bottom of the handguard. Includes two Accessory M-LOK to Picatinny Rail Sections. One Short (5 slot Picatinny) and one Medium (9 slot Picatinny) Length Picatinny Rail sections. They can be placed in any of the sides or bottom M-LOK slots.