Cov hmuv cawv yog lub npias thoob qhov hluav taws xob valve, siv rau lub thoob npias, ua ke nrog lub thoob caj dab xov foob, thiab nrog tib hom filling kab thiab dispenser,
Lub tuam txhab no muaj lub tswv yim ntawm "zoo dua, cov nqi ua haujlwm qis dua, cov nqi tsim nyog dua", yog li lawv muaj kev sib tw cov khoom zoo thiab tus nqi, yog vim li cas peb xaiv los koom tes.