custom sound volumn knob 1. cnc machining 2. fabrication service ... methodCNC turning, milling, drilling, automatic latheSurface finishChrome plating, zinc plating, blackening, Nickel plating, Electrophoresis, AnodizationColorMetal colors availableOEM & ODMAvailableRohs ComplianceAvailableFOB PortXiamen ... Send the parts by express, 3~5 days door to door service.Application Audio, MP3, MP4, earphone, ...