ABC RIFLE COMPANY AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle Red. It features a 4in 4150 CMV barrel with a 1:10 twist and a direct-blowback action compatible with both Colt and Glock style lowers. The 1/2x36 7075 aluminum flash can blast diverter controls muzzle blast in tight quarters. An 8620 nitride-finished 9mm BCG ensures smooth cycling while classic mil-spec components like the ejection port cover forward assist and forged charging handle round it out with proven reliability. Specifications for ABC RIFLE COMPANY AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle: Manufacturer: ABC RIFLE COMPANY Caliber: 9mm Luger Barrel Length: 4 in Barrel Twist Rate: 1-10 Threads per Inch: 1/2x36 Muzzle Device: Muzzle Diverter Flash Can Handguard Length: 4.5 in Gun Rail: M-LOK Gun Type: Pistol Gun Make: AR Platform Gun Model: AR-9 Bolt Carrier Group Included: MIL-SPEC Charging Handle Included: MIL-SPEC Package Contents: ABC RIFLE COMPANY AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle What firearm models does the manufacturer say ABC RIFLE COMPANY AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle is compatible with? The manufacturer suggests that ABC RIFLE COMPANY AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle is compatible with AR-9ABC RIFLE COMPANY UA9-BR4-ML4-RD: AR9 9mm Luger Pistol 4in Barrel M-LOK Handguard Complete Upper Receiver w/BCG And Charging Handle Red