1. Cov qib dej tsis sib haum ntawm cov khoom siv dej tsis sib haum yuav tsum siab, thiab nws yuav tsum ua kom tau raws li cov qauv dej tsis zoo ntawm daim ntawv thov.
2. Cov khoom siv dej tsis sib haum yuav tsum muaj cov khoom siv hluav taws xob zoo thiab cov txheej txheem kev thov kub.
3. Kev sib kis tau zoo ntawm cov khoom siv dej tsis sib haum yog siab, thiab cov khoom siv tsis muaj dej tsis zoo siv cov khoom siv nickel alloy tuaj yeem ua kom ntseeg tau tias qhov kev ua tau zoo tam sim no yuav tsis poob thaum lub sijhawm sib kis.
