Ntoo hluav taws rated qhov rooj ncej feem ntau muaj 2 kev xaiv, ib qho yog hlau thiab lwm qhov yog ntoo. Hauv Asmeskas cov neeg siv khoom lag luam nyiam xaj steel ntau dua vim tias kev ua tau zoo txhim khu kev qha.
Hauv Asmeskas kev lag luam, muaj cov qib sib txawv ntawm cov hluav taws kub xws li 20/45/60/90 feeb thiab tsuas yog 20 feeb hluav taws qhov rooj tuaj yeem mus nrog tus thav ntoo, lwm tus yuav mus tsuas yog nrog hollow hlau thav ntawv. Cov ntoo thav duab tau pom zoo dua nyob rau hauv thaj chaw tsim kho thaum lub steel thav duab muaj cov hluav taws kub zoo dua nyob rau hauv kev xav tau ntau dua hauv qhov kev ntsuas hluav taws.