... Base 1)Material: zinc alloy 2)Tolerance: +/- 0.005mm 3)Finish:Polishing , plating 4)Color:gray,white,black Lamp Base 1)Material: zinc ... , thread rolling machine, drilling machine, tapping machine, etc 2 ) Measuring & testing equipment: Projector , concentricity tester, ... tensile force tester,etc. 3 ) Materials: zinc alloy 4) Finish: Anodized, Polishing, zinc plated , nickel plated , chrome ,etc. ...