The Faithfull Hexagon Keys are six sided wrenches for driving socket screws which are used mostly on machinery for fastening parts tightly together. 15 x Imperial: 0.028, 0.035, 0.050, 1/16, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8in.