Polypropylene (PP) screw caps ndi chida chosindikizira chodalirika komanso chosunthika chomwe chimapangidwira ntchito zosiyanasiyana zonyamula. Zopangidwa ndi zinthu zolimba za polypropylene, zophimba izi zimapereka chisindikizo cholimba komanso chosamva mankhwala, kuwonetsetsa kukhulupirika kwamadzi kapena mankhwala anu.