Super Air Amplifier Shim Sets for Model 120028 include (1) .006" (0.15mm), (1) .009" (0.23mm), and (1) .015" (0.39mm) stainless steel shims. The Model 120028 8" (203mm) Super Air Amplifier is supplied with a .009" (0.23mm) air gap. Flow and force can be increased by replacing the shim with a thicker .015" (0.39mm) shim.