Knife Switch, Double Pole - Double Throw, Double Pole - Double Throwdurable Plastic Base Knife Switches That Stand Up During Tough Student Use. Poles & Knives Are Made Of Brass For Good Electrical Connections.
Double Convex round Lens, Material: Glass, designed for physics and educational uses, Because of their educational use design, there may be minor imperfections that do not affect physical function, for educational uses, Size: 100mm focal length, 2in diameter and 8mm thick
Double Concave Optical round Lens, Material: Glass, designed for physics and educational uses, Because of their educational use design, there may be minor imperfections that do not affect physical function, Size: 150mm focal length, 50mm diameter and 5.5mm thick