Or gear down-for the science fair or for any number of hobby projects. This hard-to-find set of (3) combination spur/beveled gears-for when you want gears set either straight or at 90° to one another-also has one small spur gear, plus three bushings. All in red, green, or blue plastic (we'll pick). The combo-beveled gears are 1-5/8", 1-1/4" and 27/32" dia with 3/16" bores to accept the bushings, which are 3/16" OD, 3/32" ID. The straight gear is 17/32" dia with a 1/16" half-bore. All are 24 pitch.