Slim/rugged - Troy M-LOK Aluminum BattleRail, 5.56

Really a great handguard. Rigid and aligns easily an flush with a flat top upper. I suggest buying the Troy brand barrel nut though. Most their rails use standard m4 barrel nuts and as such they produce a higher quality one. First tried on a cheaper barrel nut and had fit issues. Then used the higher priced and higher quality Troy barrel nut and installation was much easier.