Made of high quality sponge , durable and practical to use. Easy to use reusable foam filters that can be used over, so you can save money and enjoy your hot tub/spa. It is important that your water is not over chlorinated as the foam will decompose, always remove filter when using a chlorine shock treatment (not necessary to remove when using a non chlorine or shock treatment). Filter works perfectly when levels are maintained in your tub. Discoloration of the filter will occur this is normal. use a warm soapy water mixture to clean out the foam filter which will then need to be thoroughly rinsed out after with clean water to remove all the suds clean filters more often for life. Type: Water Filter Parts color:Green :sponge size:About outer diameter 10.4cm, inner diameter 5.2cm, height 8cm Package Contents: 6 x Foam Filters Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.