60-Tube Polypropylene Test Tube Rack for 16mm Tubes, 9.75" Wide Lab Supplies_Clips demonstrating mechanical-to-electrical energy conversion as

demonstrating mechanical-to-electrical energy conversion as the crank lights the bulb

Continuously variable 100V-5kV output shown on a 0-5kV digital voltmeter

and cone — on interchangeable ebonite-insulated pillars

dimensioned to slot into PH0651 optical-bench holders for repeatable image-formation

Alternate-model 75mm reading magnifier with a 20cm focal length

60-Tube Polypropylene Test Tube Rack for 16mm Tubes, 9.75" Wide Lab Supplies_Clips demonstrating mechanical-to-electrical energy conversion asStackable grid base on this polypropylene test tube rack holds 60 tubes up to 16 mm across a 9. 75 inch length for chemistry and biology student laboratories.