Features Diffenerent Size Options: the Screw extractor set includes 10 pieces of drills (sizes from #1 - #10), match 10 pieces extractor (sizes from #1 - #10),1 piece of extension bit holder (6.35 mm) & 1 socket adapter (4 mm) with storage box Precisely Machined Aggressive Multispline Teeth】The internal thread with reverse spiral flutes design to bite down to provide maximum gripping power, the more you turn, the tighter the socket grips.Each surface is precision machined and resistant to corrosion. Internal left-handed spiral design for extra grip and faster tapping. Easy Operation: Two simple steps to remove all stuck screws or bolts in a few seconds. Step One to choose a drill bit smaller than the damaged screw, Step Two to use the same size extractor to take out reversely use your electric hand drills in low Speed Feature: magnetic socket Sturdy deck will never fall off, can be firmly absorbed even when turned in work Warm Tips: Please had better install them on the electric drill (suitable for basic electric hand drill) instead of hammer drill. When stripping the damaged screw please in low speed which can avoid getting hurt. Specification: Item Type: Screw Extractor Set  Material: Plastic + alloy Model: None Color: Red Size: Approx. 100 x 150 x 42.3mm / 3.9 x 5.9 x 1.7in Package List: 1 x Connecting rod 1 x Connector 20 x Bits Note: Do not use on hard metal. Package List 1 x Connecting rod 1 x Connector 20 x Bits