Tshwj tsis yog tias tau teev tseg, iav Fiber Fabric Cloth Fiberglass Woven Roving yuav tsum muab cia rau hauv qhov chaw qhuav, txias thiab noo noo pov thawj. Qhov zoo tshaj plaws siv hauv 12 lub hlis tom qab hnub tsim khoom. Lawv yuav tsum nyob twj ywm hauv lawv cov ntim khoom qub kom txog thaum ua ntej siv. Cov khoom tsim nyog rau kev xa khoom los ntawm txoj kev nkoj, tsheb ciav hlau, lossis tsheb thauj khoom.