1. Cov kev co thiab txhim khu kev qha.
2. Daim phiaj plob yog kho tau.
3. Muaj ntau qhov chaw.
4. Kev sib thooj tshwj xeeb tuaj yeem tiv thaiv cov ntaub ntawv los ntawm txhaws.
5. Tiv thaiv cov khoom-resistant seem los ntawm kev hnav los ntawm cov ntaub ntawv me me, cais cov ntaub ntawv me me kom nce cov zis ntxiv.
6. Ib qho txawv txav ceev-kev tswj hwm-kev tswj hwm tau ntsia kom kho tau qhov ntau kom hloov cov zis pub, thiab tsis tas yuav pib lub tsheb muaj zog ntau.
7. High pib zaus
(1) Txiav txim siab tag nrho cov kab ntau lawm kom yooj yim lub siab ntawm lub puab tsaig crushing thiab counter-tawm tsam.
(2) zam dhau cov cuab yeej siv hluav taws xob siab.
