Bear Creek Arsenal BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver Bear Claw Fluted Heavy 1-8 1/2x28 Flash Hider 416R Black. 223 Wylde upper is compatible with any mil-spec AR-15 lower. Magazine not included. Specifications for Bear Creek Arsenal BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver: Manufacturer: Bear Creek Arsenal Caliber: .223 Wylde Barrel Length: 18 in Barrel Profile: Heavy Barrel Twist Rate: 1-8 Muzzle Device: Flash Hider Finish: Stainless Steel Color: Black Gun Model: AR-15 Handguard Length: 15 in Gun Rail: M-LOK Gun Make: AR Platform Barrel Material: 416R Stainless Steel Package Contents: Bear Creek Arsenal BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver What firearm models does the manufacturer say Bear Creek Arsenal BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver is compatible with? The manufacturer suggests that Bear Creek Arsenal BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver is compatible with AR-15Bear Creek Arsenal UABA357223WMHB1818SSBCF15ASR: BC-15 .223 Wylde 18in Bolt Action Style Upper Receiver Bear Claw Fluted Heavy 1-8 1/2x28 Flash Hider 416R Black