cromox โซ่ CK, G6 DIN 5687, 1.4404 cromox Chain CK, Grade 60 similar DIN 5687, AISI 316L, blasted cromox โซ่ CDK, G6 1.4404 DIN 766 cromox Chain CDK, Grade 60 AISI 316L similar to DIN 766, tested, calibrated, bright polished