Piv nrog rau lub qhov rooj hluav taws kub, steel qhov rooj hluav taws muaj cov qauv tseem ceeb dua, thiab cov khoom siv txias txias tag nrho tsis yooj yim rau kev puas tsuaj. Cov qhov rooj hluav taws yog qhov tseem ceeb hauv cov chaw pej xeem thiab ua lub luag haujlwm tseem ceeb hauv kev nyab xeeb hluav taws rau pej xeem.

hlau pem hauv ntej qhov rooj,hluav taws kub resistant qhov rooj , hluav taws kub resistant qhov rooj chaw tsim tshuaj paus ,steel qhov rooj thiab qhov rais,hlau rooj vag,hluav taws kub ntsuas qhov rooj pom vaj huam sib luag,

Lub qhov rooj kub ceev tawg iav,steel qhov rooj thiab qhov rais,hluav taws qhov rooj, hluav taws qhov rooj foob,hlau pem hauv ntej qhov rooj,hluav taws kub ntsuas qhov rooj pa luam yeeb foob,

hluav taws kub ntsuas qhov rooj pom vaj huam sib luag,tawm qhov rooj txhais, lub qhov rooj hlau qhov rooj, qhov rooj kaw thaum muaj xwm ceev