This is a 5 pack of Ultra Screen skimmer filter socks for your pool skimmer baskets. Simply stretch Ultra Screen over the rim of the skimmer basket. 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. When dirty, Ultra Screen may be removed, cleaned and reused. This filter sock is great for keeping your pool or spa crystal clean.