The Rex RX-MS-KIT Multi-Scale Durometer Kit, Includes Analog Display with Type A, B, C, D, DO, O, OO, OOO Barrels is ideal to perform hardness tests on various types of non-metallic materials. The Multi-Scale base kit consists of an analog display with a type A, D and OO durometer barrel. A complete kit is supplied with an analog display and A, D, B, C, DO, O, OO, OOO durometer barrels. Changing scales is accomplished by unscrewing one barrel and replacing it with another - no supplementary calibration or adjustments are necessary. A test block, calibrated to the selected scale is also included. The block allows the user to perform quick functional checks on the instrument. The indicator and barrels are made in the USA, and are calibrated to the ASTM-D2240 standard for durometer hardness testers.