An economical, high quality bench set that is excellent value for introductory lens work. This 74 centimeter extruded aluminum bench set allows the basic properties of lenses to be explored. The optical elements are mounted in robust molded holders that are simply pushed into sockets in the riders. Each rider can accept up to three elements. The riders slide freely on the aluminum bench until an optical element is pushed in, when the rider locks in place. This eliminates accidental repositioning and allows the entire lightweight setup to be carried around without anything falling off. The LED-illuminated object is self-contained (powered by an AAA battery– no cables!) and generates bright, clear images on the opaque screen. Four high quality lenses are included, all with 50mm diameter.