A reader says this is the smallest open-end wrench in the world, with 0.005 in. across the flats on one end and 0.010 in. across the other. The human hair next to the wrench gives a comparative size. The wrench was made with an Agie Vertex EDM using 0.0008 in. tungsten wire. Marsh Syverson President, Engineering Techniques, Inc. San Jose, Calif.