screw extractor,square type 1.size No.1-7 2.material: alloy steel ... steel 3.black finished or sand blasted Description:screw extractor,square typeSpecification:No.1:. M3-6,1/8-1/4No.2 ... /4No.6: M18-24,3/4-1"No.7: M24-33,1"-1 3/8"Special requirments:Heat treatmentblack finished, or ...