Features This screw extractor set is designed to remove broken studs and bolts Made of high quality Chrome vanadium steel material,and treated by heat treatment,with high hardness and wear resistance Reverse spiral design for maximum grip, so helps relieving your labor Recommended drill bit size (for location hole) etched on each extractor,suitable for high torque applications This product contains 10 pcs different size extractors of 3.2-10.3mm, so can meet your repair work under different circumstances Descriptions:This screw extractor set is designed to remove broken studs and bolts. Made of high quality Chrome vanadium steel material, and treated by heat treatment, with high hardness and wear resistance. And contains 10 pcs different size extractors of 3.2-10.3mm, so can meet your repair work under different circumstances.. Specifications:Material: vanadium steel Color: grayQuantity: 10 pcsWeight: 537gSize: 1/8"(3.2mm), 5/32"(4mm), 3/16"(4.8mm), 7/32"(5.5mm),1/4"(6.3mm),          9/32"(7mm), 5/16"(8mm), 11/32"(8.7mm), 3/8"(9.5mm), 13/32"(10.3mm) Package Included:10 x Screw Extractor 1 x Red Case Package List