Each shim set ships with QTY 1 of Shim 1 (largest), QTY 8 of Shim 2 (medium), and QTY 1 of Shim 3 (smallest). The large shim can be used to give the installer one half of a rotation or as a spacer for barrels that do not have relief cuts behind the threads. Shim 2 is used in varying quantities to achieve the proper alignment of your muzzle device. This shim gives the installer approximately 45 degrees of rotation. If needed, Shim 3 can be used where smaller degrees of rotation are needed for proper alignment.