Check the listing for details. Precision Armament Accu-Washer Muzzle Device Alignment System 1/2-28 Thread 18pk. Color: Gray, Condition: New. Listed at 26.95 USD. Accu-Washer kit includes 18 individually marked high precision shims of different thicknesses allowing 360 degree indexing in 20 degree increments. Only one shim is required for each application.PRECISION MACHINED Each Accu-Washer shim is machined to a guaranteed thickness uniformity of ±0.0001” providing better muzzle device alignment than any other system on the market.NO TOLERANCE STACK-UPS The single shim system eliminates tolerance stackups inherent with stacked-shim systems resulting in superior alignment and accuracy.CONTROLLED TORQUE Precise 20 degree indexing increments prevents the need for excessive installation torque which can cause muzzle distortion and adversely affect accuracy.SIMPLE TO USE Each Accu-Washer shim is individually marked according to thickness, simply choose the correct size and install. No need for the time consuming hassle involved with peel washers and stacked-shim systems. MAXIMUM SAFETY Ensures the lowest risk of baffle strikes for the highest level of safety on alignment critical devices such as sound suppressors and muzzle brakes.COST EFFECTIVE One kit will index about nine muzzle devices on average. Inexpensive replenishment shims are available and can be purchased individually as needed.CORROSION RESISTANT Machined from high strength 400 series stainless steel bar. Finished with an oxide blasted non-reflective surface for low visibility.IMPACT RESISTANT Solid monolithic design provides the bearing strength necessary to withstand hard front and side impacts without deforming and causing dangerous misalignment. Specifications:Material: 400-series stainless steelFinish: Oxide blasted, matte grey1/2-28 ThreadO.D.: 0.750″Thickness: 0.060″-0.094″