Includes four precision molded nylon drums. All drums are infinitely adjustable within range. No tools are required for adjustment. A graduated adjsutment key is included with each drum. Each turn of the adjusting screw is .1cc or about 1 grain of powder. Each key is marked with .01cc graduations allowing easy 1/10 grain powder adjustments. Quick Change Drum Set can be used in conjunction with the Deluxe Perfect Powder Measure and Auto Drum Powder Measure.