Pocket-Size Micro Inside Caliper is 40% smaller than standard analog calipers. Perfect for measuring small wood-turnings and any other project requiring precise replication of sizes and distances, including setting the distance from a table saw blade to a fence, drill press and milling machine setups, and more. All-steel caliper is 4" long and measures from approximately. 5/16" to 3-1/8". Best of all, no batteries are required!