Nyom laj kab feem ntau yog ua los ntawm PVC thiab Hlau Hlau, uas muaj zog heev thiab ruaj tiv thaiv tshav ntuj. Nws mus los ntawm ntau cov txheej txheem thiab yog li nce nws cov durability. Cov laj kab no ua los ntawm cov xov hlau galvanized ntom ntom; nws tsis hlawv los yog, nyob rau hauv lwm yam lus, tsis ignite. Tsis yog rau kev ruaj ntseg thiab kev ua haujlwm xwb; yog cov qauv uas tseem tiv thaiv cov duab tsis zoo.