KidWind Wind Turbine Hub, ten-pack of 12-hole crimping hubs, made from recycled plastic, allows you to turn any DC generator into a wind turbine, Diameter: 2.25 in, Maximum number of dowels: 12, Size of shaft hub press fits onto: 2 mm
Spectrum Discharge Tube, Mercury Gas to show spectral lines of pure substances. Tubes approximately 260mm long, central capillary portion approximately 3-1/2 to 4 (90-100mm) long with electrodes sealed at both ends and connected to lead wires protected by metal caps