Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group BCG DLC Coated Black. Low Mass Carrier is 1.7 ounces lighter than the Full Mass Carrier. Made specifically for competition shooters. Specifications for Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group (BCG): Manufacturer: Sharps Rifle Company Color: Black Finish: DLC Fabric/Material: Steel Carrier Material: S7 Tool Steel Caliber: .223 Remington Gun Make: AR Platform Gun Model: M16 M4 AR-15 Hand: Right Features of Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group Batch MPI and HPT tested Tensile Strengths of 1550-1600 mpa or 220000-235000 psi. Toughness over 200ft/lb Charpy C-Notch HRC of 46 yields a 15percent increase in hardness at the same toughness comparing to Carpenter 158 & 9310 Package Contents: Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group What firearm models does the manufacturer say Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group (BCG) is compatible with? The manufacturer suggests that Sharps Rifle Company Low Mass Xtreme Performance Bolt XPB Carrier Group (BCG) is compatible with AR-15 M4 M16Sharps Rifle Company SRCXPBCGLOW: Low Mass Xtreme Performance Bolt XPB Carrier Group DLC Coated Black