1.Product Set Size?a?a26 pcs bolt screw extractor includes 13 bolt extractors (1/4', 5/16'(8mm), 3/8', 10mm, 7/16'(11mm), 12mm, 1/2', 13mm, 9/16'(14mm), 5/8'(16mm), 17mm, 11/16', 3/4'(19mm)); 6 lefthand drill bits (3/8', 9/32', 1/4', 5/32', 1/8', 3/32'); 6 spiral screw extractors (1, 2, 3, 4, 5, 6), and 1 hex adapter (1/4'3/8'). 2.High Hardness Durability?a?aThe bolt screw extractor set is made from CrMo steel and 4341/6542 HSS, this set excellent durability, corrosion resistance, and hardness, and can be repeated use without worrying about breakage. 3.Nut Remover Adapter?a?aReverse spiral groove design provides maximum grip and torque for fixing bolts. The standard 3/8inch drive with a 1/4'3/8' hex adapter works with impact wrenches, tap handles, and ratchet wrenches to extract metric and standard fasteners, such as frozen, rusted, damaged, stripped, round, and hex head bolts, nuts, screws. 4.Lefthand Drill Bit Spiral Screw Extractors: Titaniumcoated HSS drill bits with 135?? angles cut easily with less resistance, while lefthand flutes clear debris to reduce friction. Use with impact wrenches for better drilling results on broken bolts. Spiral screw extractors provide a strong grip to remove broken bolts and screws from wood through drilled holes.