Ib qho tseem ceeb ntawm lub qhov rooj iav qhov rooj yog qhov txhuas pob tshab seem qhov rooj. Hom lub qhov rooj no yog qhov tshwj xeeb tshaj yog rau kev lag luam kev lag luam xws li chaw nres tsheb, kev ntxuav tsheb, thiab cov chaw muag tsheb, qhov kev pom zoo yog qhov tseem ceeb hauv kev nyiam thiab txais tos cov neeg siv khoom. Ntxiv mus, cov qhov rooj no yog huab cua-resistant, kom ntseeg tau tias lawv muaj peev xwm tiv taus sab nraum zoov tej yam kev mob thaum ua kom lub sab hauv zoo thiab ruaj ntseg.