HDX Folding Hex Key Set (17-piece) HDX 17-Piece SAE/Metric Folding Hex Key Set. These keys resist rotational distortion.The set has a comfortable over molded ergonomic grip. SAE hex key set: 7/32, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, 3/16, 1/4 in. MM hex key set: 1.5, 2, 2.5, 3, 4, 5, 6, 8 mm.