The NEIKO 10288A Hex Bit Socket Set is 32 pieces of SAE and Metric commonly used allen head sizes for fitting on a ratchet. SAE: 1/4-inch drive sizes – 5/64”, 3/32”, 1/8”, 5/32”, 3/16”, 7/32”, 1/4"; 3/8”-inch drive sizes – 9/32”, 5/16”, 3/8”, 7/16”, 1/2"; 1/2-inch drive sizes – 9/16”, 5/8”, 11/16”, 3/4" METRIC: 1/4-inch drive sizes – 2, 2.5, 3 ,4, 5, 5.5, 6 millimeter; 3/8-inch drive sizes – 7, 8, 9, 10, 12 millimeter; 1/2"-inch drive sizes – 14, 15, 17, 19 millimeter. With S2 steel construction that are precision machined, you get a secure fit with minimizing round-off of your bits, so they last for years. Each hex bit has your most common Allen head sizes to give you the versatility of finding the right fit for every job. Trust in NEIKO for your allen wrench socket needs!