The UTG Pro M 4/15 Rifle 15" Super Slim Free Float Handguard is free-floating with proprietary attachment design and a compact profile. Lightweight with rail at 12 o'clock position forms a continuous picatinny top section. Includes 3 user detachable 2-slot rail sections for 3, 6 and 9 o'clock positions. Integral anti-rotation tab for locking, accommodates low profile gas block and ergonomic slim tubular profile for positive handling. Made in USA NOTE: This rail system is designed to fit with standard AR15 gas tubes. The compatibility with any special piston system is not guaranteed. Also, the rail system works with standard AR15 upper receivers. It may not be compatible with any re-designed, over sized upper receiver.