Coal mine baskets, destined rau kev siv subterranean, muab ib daim ntawv pov thawj kev nyab xeeb thee rau kev ua raws.
Cov khoom tawg-pov thawj uas tsis yog siv rau hauv av tuaj yeem hloov mus rau Zone 2 tawg-pov thawj cov qauv thiab tsis tas yuav tsum muaj daim ntawv pov thawj kev nyab xeeb ntawm cov thee. Txawm li cas los xij, rau kev siv hauv av, daim ntawv pov thawj kev nyab xeeb thee yog qhov yuav tsum tau ua thiab tsis tuaj yeem sib tham.