Pulley Large Demonstration Single, Designed for Classroom Demonstrations, Light-weight, low-friction, and deformation-resistant plastic ensures accurate results, Open to make it easier for users to run pulley cords through them
Optics Kit - Junior, 2.6lbs, 15.0x11.4x4.3inch, ray box with bulb and flex having two 4 mm plugs, a pair of blanking plates, two slit plates, Planoconvex lens, color mixing set, frosted concave lens, frosted convex lens, frosted semicircular lens