Dimensions: inner diameter: 1.57 inches/4 cm, outer diameter: 4.25 inches / 10.8 cm, the length of the swimming pool filter is 2.87 inches / 7.3 cm.High Quality: The Hot Tub Filter is made of sponge, soft and durable, with good flexibility, not easy to deformed or break.Easy to care: The filter sponge can keep the water clean and reduce bacterial in your pool, can be washed and re-used several times over, easier to clean and maintain than traditional paper filters.Reusable: This Foam filter will outlast your paper cartridges and can be washed and re-used several times over.Application: Suitable for Bubble & Jetted Pure-spas, replaces the S1 type paper cartridge.Type: Filter Spongecolour: whiteMaterial: spongePackage Contents:4 x Swimming Pool FilterOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.