1. Tiv thaiv cov khoom thiab tiv thaiv kev txhuam;
2. Cov khoom yog hloov tau, txo qhov puas tsuaj rau cov khoom vim kev sib tsoo;
3. Lub teeb yuag thiab xis, nws kuj tuaj yeem nqa thiab siv tau nyob ib leeg;
4. Zam lub ntsej muag tsos qauv;
5. Tsis muaj qhov deformation tom qab siv ntev;
6. Los tiv thaiv plua plav, tiv thaiv static, tiv thaiv khawb;
7. Dej tsis qab ntsev thiab airtight, tuaj yeem ntxuav tawm ntau zaus.
