Drywall screws: Features: Coarse thread, Fine thread Raw material: Carbon steel 1022 Head type: Bugle head The size : 3.5*16-4.8*152; #6* 5/8-#10*6   Finish:Hardened,Z.P,Black Phosphated,Grey Phosphated Driver:Phillips,Pozi,Square,Torx recess Chipboard screws Features: Coarse thread, Fine thread, With or without rid Raw material: Carbon steel 1022 Head type: Countersunk head or Flat head, Pan head, Oval head Diameter: 3.0mm-6.0mm Length: 10mm-200mm Finish: Hardened,Z.P,Black Phosphated     Self-drilling screws Raw material: Carbon steel 1022 Head type: Modified trussed, bugle head, pan framing head Driver: Phillips, Pozi,Square,Torx recess Diameter: 3.5mm-4.8mm Length: 10mm-200mm Finish: Hardened,Z.P,,Black Phosphated,Grey Phosphated