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 Automatics Geissele 5.56mm Reliability Enhanced Bolt Carrier & Gas Key 05-2992