Hawkins Precision Tank ST Self-Timing Muzzle Brake 7mm Black. The Tank ST features a self-timing locking collar design made in collaboration with Southern Precision Rifles. This unique design allows the user to install their brake and lock down the collar so it times on the barrel exactly the same way every time its installed.Its straight 4-port design cuts recoil while also producing less concussion and blow back on the shooter. This reduces shooter fatigue over long strings of fire or long days of shooting at precision rifle matches. The ports are also designed to collect less carbon and thus need less maintenance.The Tank ST features a 3/8 Hex Bit opening up front so users can torque down their muzzle brake to the same torque value every time. This combined with the locking collar allows for consistent mounting with minimal to no POI shift when removing and reinstalling. (Recommended 65 in-lbs. to 100 in-lbs.)made in specialized factories out of 17-4 Stainless Steel the Tank ST comes in 6mm 6.5mm 7mm and 30 cal variants. Outside diameter is .990 5/8-24 thread. Specifications for Hawkins Precision Tank ST Self-Timing Muzzle Brake: Manufacturer: Hawkins Precision Color: Black Fabric/Material: 17-4 Stainless Steel Threads per Inch: 5/8x24 Outer Diameter: 0.99 in Length: 1 in Weight: 3.74 oz Features of Hawkins Precision Tank ST Self-Timing Muzzle Brake 4-Port Muzzle Brake with self timing and lockable collar Package Contents: Hawkins Precision Tank ST Self-Timing Muzzle Brake Hawkins Precision 104-1000-7mm: Tank ST Self-Timing Muzzle Brake 7mm Black