Precision Reflex 223 Straight QC Brake Crown Black. Specs: 304 Stainless .95in dia. X 2.25in long thread is 1/2 x 28. 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 brake into place using a round screw driver in the 1st slot closest to the barrel. The end of the brake has a series of points (crown ) for an aggressive look. Specifications for Precision Reflex 223 Straight QC Brakes Crown: Manufacturer: Precision Reflex Caliber: 5.56x45mm NATO .223 Remington Fabric/Material: Stainless Steel Threads per Inch: 1/2x28 Gun Make: AR Platform Outer Diameter: 0.95 in Length: 3 in Weight: 4.3 oz Additional Features: Crown front end Included Accessories: Spacer shims Diameter: 0.95 in Package Contents: Precision Reflex 223 Straight QC Brakes Crown Precision Reflex 05-0095B: 223 Straight QC Brake Crown Black