The rails slip in perfectly and there are no sharp edges at all. This is a perfect fit for your AR with a front sight post. Once I figured out I had to put it in at an Angle I'm very happy, instead of paying 170 for the bcm quadrail to go with my bcm4 I'm definitely ok to have this on can't tell the difference I was very happy with the quality and ended up buying 5 more sets. I bought two sets to see if they were any good. Type 2 Class III Mil-Spec hard coat anodizedĠ of 0 people found the following review helpful:.Machined from 6061/T651 Aircraft Grade Aluminum.Five built-in anti-rotate sockets for QD sling swivels.Four MIL-STD Picatinny rails at 12, 3, 6, and 9 o'clock.No modifications to the firearm are required.The precision machined rails enable consistent repeat of zero for any accuracy dependent devices such as optics or lasers. The AU design ensures a secure fit with no movement on the weapon while providing a solid mounting platform for accessories. Rails are located at the 12, 3, 6 and 9 o'clock positions, there are also 5 quick detach anti-rotate swivel ports located throughout for ideal sling attachment. They mount exactly like the factory hand guards but dissipate heat much more efficiently. The AU 7' Drop-In Carbine Length Quad Rail is a high quality 2-piece picatinny forend replacement for all mil-spec AR15/M4 carbine length plastic hand guards. AU 7' Drop-In AR15/M4 Carbine Length Quad Rail Description:

Quad rail handguards m4 carbine