【 Compatible Models 】The replacement cartridge filters are compatible for RELXTIME all spa pools. ※Note: All referenced manufacturers' names and part numbers are the trademarks of their respective owners. Mentioned for compatibility purposes only. 【Inflatable Hot Tub Filters Specifications 】 Diameter: 3.9"; Length: 3.1"; Top End Cap Style: Open Top, Bottom End Cap Style: Closed, Filter Material: Trilobal Filtration Fabric. 【 Premium Filtration Performance 】 Innovated "Dirt-Locking" technology makes the fabric traps much more contaminants than regular fabric. This filter efficiently removes hair, leaves, dust, sediment, sand, etc. Enjoy clean leisure time in your pool and spa. 【 Easy To Clean&Install 】 Uniformity and high-performance trilobal fabric make it easier to capture and release stains, so it's easy for you to wash the filter after use. It is recommended that you replace cartridges every 2 weeks to maximize your spa's performance. 【 After-sales Guarantee 】 We Value our customer shopping experience, after you place the order, if you have any problems about our product, please contact us freely, we'll do our best to solve it for you within 24 hours. Hot Tub Replacement Filter Cartridges Compatible with All RELXTIME Hot Tub, All ALEKO Hot Tub, Wejoy Hot Tub Aquaspa, Screw-in Hot Tub Filter, Compatible with Many Massage Pool Models