School Smart Coin Envelope with Gummed Flap Closure, 28 lb, 2-1/2 X 4-1/4 in, Kraft, Brown, Pack of 500 Kit includes: 16 economy bulb holders, 16 miniature bulb, 16 battery holders, 2 motors, 1 electricity Teacher's guide, 16 economy switches, 10 wire connectors, 16 D batteries, 2 buzzers