Cov phaj hluav taws xob tsis sib haum yog cov hluav taws xob hloov pauv ntau dua-hom kub hloov pauv. Nws muaj ntau cov hlau corrugated daim hlau hloov txheej txheem ntawm, thiab qhov chaw txias thiab kub kub yog tsim los ntawm roj hmab sib khi gaskets kom paub txog tag nrho cov khoom siv sib hloov cov cua sov.
