WIDE USE: Each of the bolt extractor can easily and quickly extract stubborn, rusted, cracked, damaged or stripped screws, studs, bolts, fastener or nut ect. Spiral and featuring a pointing tip can firmly embed the extractor into the damaged screws or others for extra resistance and ideal gripping power for easier removal. EASY TO USE: The screw extractor kit can take out various stuck screws by two steps within 10 secs. Use proper size drill bit to bore a hole on screw head, then reverse the remover counterclockwise into the damaged screw until it is released. ABOUT SIZE: The screw extractor drill bit set in 6 different sizes to meet varied needs. ; They are 3/4"-1", 9/16"-3/4", 7/16"-9/16", 5/16"-7/16", 1/4"-5/16", and 1/8"-1/4". The full broken screw extractor comes in a molded plastic storage case. ABOUT MATERIAL: This stripped screw extractor is made of high-quality tool steel. With high hardness and high torque though strict process setting, tempered twice and surface polishing. Size: Variety Pack Material: Plastic Finish type: Polished Number of pieces: 6