USED Jacob Grey Firearms Cobra Billet Muzzle Brake .30 Cal 5/8x24 Thread Flat Stainless Unfinished CMBFSTN. 30 Carbine Finish: Class III Hard Anodized Fabric/Material: Steel Threads per Inch: 5/8x24 Gun Make: AR Platform Gun Model: AR-9 Inner Diameter: 0.34 in Length: 3.2 in Weight: 4.5 oz Additional Features: Flat Package Contents: Jacob Grey Firearms Cobra Billet Muzzle Brake What firearm models does the manufacturer say Jacob Grey Firearms Cobra Billet Muzzle Brake is compatible with? The manufacturer says that Jacob Grey Firearms Cobra Billet Muzzle Brake is compatible with AR-9Jacob Grey Firearms CMBFSTN: Cobra Billet Muzzle Brake .30 Cal 5/8x24 Thread Flat Stainless Unfinished