Bear Creek Arsenal BC-15 6mm ARC 18in Right Side Upper Receiver Heavy Mid 1-8 5/8x24 Flash Hider Parkerized Tungsten. Specifications for Bear Creek Arsenal BC-15 6mm ARC 18in Right Side Upper Receiver: Manufacturer: Bear Creek Arsenal Caliber: 6mm ARC Barrel Length: 18 in Barrel Profile: Heavy Gas System Length: Mid Length Barrel Twist Rate: 1-8 Threads per Inch: 5/8x24 Muzzle Device: Flash Hider Finish: Parkerized Gun Model: AR-15 Handguard Length: 15 in Gun Rail: M-LOK Gun Make: AR Platform Weight: 6 lb Flutes: No Package Contents: Bear Creek Arsenal BC-15 6mm ARC 18in Right Side Upper Receiver What firearm models does the manufacturer say Bear Creek Arsenal BC-15 6mm ARC 18in Right Side Upper Receiver is compatible with? The manufacturer suggests that Bear Creek Arsenal BC-15 6mm ARC 18in Right Side Upper Receiver is compatible with AR-15Bear Creek Arsenal UASCC50356MMAMHB181815TNGSR: BC-15 6mm ARC 18in Right Side Upper Receiver Heavy Mid 1-8 5/8x24 Flash Hider Parkerized Tungsten