±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

Tirrill burner on a stable octagonal base adds air

Binaural stethoscope with PVC tubing provides clear heart and lung sound detection for medical and nursing education

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

±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.