Ib qho yog tias qhov chaw ua haujlwm ntawm lub nruas yog qhov ntub los yog av nkos, thiab cov av noo hauv qhov chaw ua haujlwm hnyav dhau, ua rau lub nruas plam;
Qhov thib ob, kev xaiv tsis raug ntawm cov roj hmab daim hlau yuav ua rau tsis txaus los tiv thaiv plam thiab hnav tsis kam ua kom tau raws li qhov xav tau ntawm qhov chaw;
Thib peb, cov khoom thauj khoom muaj cov dej noo ntau, uas nkag mus rau hauv cov roj hmab ntawm lub nruas, ua rau lub nruas nto plam thiab ua raws li cov khoom siv.
Raws li paub zoo, cov menyuam coated roj hmab daim hlau feem ntau muab faib ua peb hom, uas yog cov roj hmab hnav-tiv taus, pob zeb diamond hnav-resistant roj hmab daim hlau, thiab ceramic hnav-resistant roj hmab daim hlau. Nyob rau hauv cov ntaub ntawv no, pav ca hnav-resistant roj hmab daim hlau yog twv yuav raug hu tsis pom zoo, raws li lawv tuav yog kuj tsis muaj zog thiab yog haum rau cov menyuam coated roj hmab kho nyob rau hauv qhuav ib puag ncig.
