Spare 500g Iron Hooked Weight with Retractable Hook Subject_Astronomy Alternate-model 75mm double-convex glass lens

Alternate-model 75mm double-convex glass lens at 300mm focal length

Converts chemical energy to electrical through a zinc-copper-sulfate redox couple

bending measurably under heat as differential thermal expansion of the two bonded metals drives the visible curvature

near-collimated for astronomical analogue and long-throw projection setups

Thirty-five-component electronics kit extending the Electronics System 1 set with capacitors

Spare 500g Iron Hooked Weight with Retractable Hook Subject_Astronomy Alternate-model 75mm double-convex glass lensCast iron 500g mass carries a retractable hook for suspension from spring scales, pulleys, or beams, serving as a replacement piece for gravitational and force measurement setups.