Reading Magnifier, 50mm, 12cm Focal Length Capacity_125mL this air-cooled rheostat carries a

this air-cooled rheostat carries a slide-bar carriage on a vitreous-enameled tube for variable resistance under thermal load

and phase-change experiments

and 2 quadruple pulleys on a heavy composite base with capstan

Higher-output 65-watt soldering iron with a wooden bakelite handle

Wooden-frame abacus with three U-shaped steel wires carrying 20 plastic beads each on a 13 by 6 inch base

Reading Magnifier, 50mm, 12cm Focal Length Capacity_125mL this air-cooled rheostat carries aChrome plated metal framed 50mm reading magnifier with a 12cm focal length, sized for fine print reading and convex lens image formation work in introductory optics.