Many and a growing number of AR owners considers the LaRue Tactical the best quality in finish, dimensions and they have a locking design to prevent the handguard from loosening which was a common problem of the first generation of free float rails in the field.
LaRue 9.0 rails on my Colt AR6721 AR-15A3 Tactical Carbine with Global Tactical-Rock Creek, mid length gas system, medium contour, 1/7, chrome lined, 16" barrel which is my heavy duty, general purpose carbine.
I only need my Surefire M961C weapon light and TangoDown vertical forward grip mounted on my rails.
I prefer the Knight's Armament Co. M4 RAS drop in two piece rails on my LMT M4 carbine for close defense work.