±2.5mA DC Interchangeable Dial for Demonstration Meter Glass Sets & Apparatus_Organic Chemistry Sets Wooden fulcrum-balance simple-machine model with

Wooden fulcrum-balance simple-machine model with a sliding pivot

Life-size right lung separates into two parts exposing bronchial tree and alveolar structure

Five-centimeter brass sphere mounted on an ebonite-insulated metal base

supporting reproductive cell biology teaching

Universal laboratory clamp holder with dual 360-degree boss head rotation

±2.5mA DC Interchangeable Dial for Demonstration Meter Glass Sets & Apparatus_Organic Chemistry Sets Wooden fulcrum-balance simple-machine model withPlus or minus 2. 5mA DC interchangeable scale on a 315x115mm laminated panel with integrated shunt, sized to drop into the demonstration meter and reconfigure it as a center zero ammeter.