Precision Reflex MSTN QC Brake 6.8mm SPC Black Black. Specs: 304 Stainless .95in dia. X 2.05in long thread is 5/8in- 24in The thread end of the brake tapers down to a .750in diameter. The brake comes with a selection of spacer shims to set the timing of the brake. The 3 holes should be at the 1 O'clock position when tightened into place. Tighten the brake into place using a round screw driver in the 1st slot closest to the barrel. Specifications for Precision Reflex MSTN QC Brakes 6.8mm: Manufacturer: Precision Reflex Caliber: 6.8mm Remington SPC Fabric/Material: Stainless Steel Threads per Inch: 5/8x24 Gun Make: AR Platform Outer Diameter: 0.95 in Length: 2 in Weight: 3.2 oz Included Accessories: Spacer shims Condition: New Diameter: 0.95 in Package Contents: Precision Reflex MSTN QC Brakes 6.8mm Precision Reflex 05-0088B: MSTN QC Brake 6.8mm SPC Black Black