ScienceWiz - Bulb and Holder with Screw in Base (Pack of 2) AWARD WINNING ScienceWiz curriculum is designed to teach kids science in an intuitive and natural progression Explore the pathways of electricity with this set of bulbs and holders from the award winning science experiment creator, Science Wiz Each package includes two 2" diameter holders with two screw-in lightbulbs Spring clips on the holder makes it easy to securely attach wires Intended to be parts for use with science projects, science fairs, etc. and are provided with minimal to no operating instructions