Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts Built for vacuum filtration

Built for vacuum filtration

Rotary-knob resistance substitution board offering twelve discrete values from 33 ohms to 10M ohms with 4mm lead connections

providing the cleanest hand-operated way to make and break a circuit during early electricity instruction with stackable modules

Square-topped wooden screw simple-machine model with a leverage block

Sturdier-than-glass metal displacement vessel at 100 by 50mm with a side spout

Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts Built for vacuum filtrationOptically worked double concave glass lens at 75mm diameter and 150mm focal length, the diverging curvature producing virtual upright images for refraction and beam spreading work.