... : carbon alloy steel size: 1/4"~1",M4~M24 surface: DAC,plain. zinc HDG ISO9001 T&Y HARDWARE INDUSRY CO.,LTD ... length within 200mm4Head diametre rangethe largest is 35mm5Surface treatmentZinc,Passivated,Dac,Geomet,H.D.G,Nickle6Heat treatmentsoft, case harden, Grade4.8 ...