Optimize your AR15 with Geissele’s Reliability Enhancement Bolt Carrier. Developed over the course of several years, this 5.56mm full-mass, full-auto rated bolt carrier features a properly torqued and staked, chrome-lined, nano-coated gas key and extended upper rails on the carrier greatly enhance stability and feeding dependability. Features of the 5.56mm Reliability Enhanced Bolt Carrier & Gas KeyGas Key – Properly torqued and stakedCarrier Rails – Extended for greater stability and significantly increased feeding reliabilityNanoweapon Durable Solid Lubricant – Extreme resistance to corrosion, wear, and abrasion, as well as rejecting carbon fouling to allow the firearm to operate normally with less lubrication Geissele 5.56mm Reliability Enhanced Bolt Carrier & Gas Key 05-2992