Click to expand Tap to zoom FILTER CARTRIDGE BASE, BASE ONLY FOR MSPA HOT TUBS & SPA $29.00 | / Tax SKU US-HS-AM-FCBO 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart Size : 7.5 x 8.5cm (2.95” x 3.3”).