Fab drop in quad rail carbine length - FAB Defense NFR Carbine Length M16 Aluminum Quad Rail

Very well made. Fit onto a Colt 6720 perfectly. I used a handguard tool to install it, then used removable carry handle to span between the upper and the handguard top rail in order to line them up and then I installed the four screws that hold the top and bottom parts of the handguard together. Now it is rock solid with no wiggle. There is a small 1/8 inch gap between the top rail and the flattop uper rail. It has QD sling holes on the sides of the rails which is nice. The one I ordered also came with three rubber rail covers. The machine work is high quality, on par with Troy or MI in my opinion. There are no sharp edges on the rails like the cheap quad rails have. The finish is quality. I think that it is extremely well made and good purchase.