Maxim Defense MXM47838 Roller Delayed Blowback System Buffer CQB Fits Most 9mm Luger AR-15/AR-9 (Maxim Defense CQB Buffer Tube Only) $180.65
Ergo 4332BK WedgeLok Slot Cover Black Rubber, 4 Slot Low Profile w/Aggressive Texture 4 Per Pack $17.10