... 3)Finish:Polishing , plating 4)Color:gray,white,black led lamp cover 1)Material: zinc alloy2)Tolerance: +/- 0.005mm 3)Finish ... machine, drilling machine, tapping machine, etc 2 ) Measuring & testing equipment: Projector , concentricity tester, hardness tester, roughness tester, torsion tester, tensile force ...