Crystal Resonator Shell 1.ROHS compliant 2.ISO9001:2000 certified 3.OEM service ... 20*20...3.surface treatment:weld,sintering ,polishing,sand blast4.bottom case:silver-alloy brazing,tin soldering5.other sizes and types ... ,Turning machine,Grinding machine,etc.Certification:ROHS Compliant Crystal Resonator Shell