Steel: Each screw extractor is high hardness steel and has heat-treated for durability.Every etching size is very clear with high visiblity for quick identification. Powerful: This bolt extractor is designed with internal thread that has reverse spirals grooves designed can be occluded to provide maximums.Each surfaces is precisions machined and resistant to. Wide Application: This bolt remover is easy to remove the and screws,bolt and slip teeth,or can be used with a variety of square drive wrenches for a wide ranges of applications. Upgraded Bolt Extractor : Compared to the old extractor,this new screw extractor does not require the socket to be placed on the hexhead before spanners is used.It's more convenient,The 3/8 inch drive design makes the screw removal device suitable for hand tools,electric or pneumatic tools Multi-Size: The screw extractor sets ranges from 1/8 inch (3.5mm) to 7/8 inch (23mm).It has 1/32 inch increments and come with a storage box,which is very convenient to store these screw extractor.