This set is designed for removing damaged, rusty or stripped screws, studs, bolts, staples. Steel screw bits, high hardness, good polishing, durable to use < p>High quality tool steel extractors with a left hand spiral flute designed for increased gripping power Easy to use, simply drill a hole in the center of the broken screw first with a suitable drill bit , then use a suitable extractor to remove the screw Kit consists of 5 extractors, 5 screw bits, well packed in a plastic storage box. </ p> Specifications: -Material: Steel -Drill Sizes: 3/32, 1/8, 3/16, 1/4, 5/16, 3/8 -Screw extractors: 1 (Dia: 4.0mm/0.15) for 4-6mm/0.15-0.23 2 (Dia: 4.5mm/0.17) for 6-8mm/0.23-0.31 3 (Dia: 6.5mm/0.25) for 8-11mm/0.31-0.43 4 (Dia: 7.5mm/0.29) for 11-14mm/0.43-0.55 5 (Dia: 11.0mm/0.43) for 14-18mm/0.55-0.70 6 (Dia: 15.0mm/0.59) for 18-25mm/0.70-0.98 -Box size: approx. 19 x 10 x 4.5cm Package content: < p>1 × Set of 6pcs screw extractors and 6pcs drill bits