General description 100% Brand New and High Quality, these Reusable Foam Box Filters are suitable for Bubble and Jetted Pure Spas as a replacement for S1 Cardboard filters. Replacing the filter elements of the paper filter is an essential part of daily pool maintenance. The cleaning and reusable foam filters will help reduce your costs over time. Technical specifications Size: 10.8 x 7.3 cm Center hole drilling: about 4 cm Color: Blue Material: Sponge Package Contents 18 x Filter Sponges Other information Note: Light shooting and different displays may cause the color of the item to differ slightly from the real thing. The measurement allowed error is +/- 1-3 cm.