SPECIFICATIONS - Outer Diameter: 5-5/16” Length: 30-1/8” Top Style: 2-1/8” Open Bottom Style: 2-1/8” Open QUALITY REPLACEMENT - Compatible with Pleatco PCST120, Filbur FC-2976, Unicel C-5351, Waterway 817-0147, and Waterway / Coast Spas Top Load (In-Line) 135 Hot Tub Spa Filters PREMIUM MEDIA - SpiroPure pool and spa filter cartridges offer long-lasting, durable filter media with high dirt holding capacity for clear, sparkling water in your pool or hot tub spa DURABLE CORE - A strong inner core means increased strength without hindering water flow or filtration performance EASY INSTALLATION - Easy to install, durable filter cartridges that allow for high filtration performance and efficiency

SpiroPure SP-PS-2976 Hottub Spa Pool Filter Replacement Cartridge. Easy to install, durable filter cartridges that allow for high filtration performance and efficiency.