Rola-Chem® US12 Ultra Screen Skimmer Basket Liner. Ultra Screen is incredible! Consisting of an extremely fine mesh material bound to a durable elastic ring, Ultra Screen prevents debris, scum, and bugs from clogging the filtering system, thereby allowing for maximum water flow and extending filter life. Simply stretch Ultra Screen over the rim of the skimmer basket. When dirty, Ultra Screen may be removed, cleaned and reused.