PLF6541-397 Spa Filter Cartridge fits 880 series 09′-23′ FC-2772 AK-80802- 1pk. Specifications? The 6541-397 is compatible with the Sundance Spa 880 Series and includes the outer filter 6473-165 and the inner filter 6473-164. Inner Filter Length: 18 3/4″, Inner Filter Dimension: 5 5/8″; Inner Filter Top Open Hole: 2 3/8″; Inner Filter Bottom Open Hole: 2 3/8″. Outer Filter Length: 19 1/8”; Outer Filter Dimension: 8 3/8; Outer Filter Top: 2 3/16” slip; Outer Filter Bottom: 4 7/16” open. Filtration Area: 80 sq. NOTE: This is a compatible part. Original manufacturers’ names and part numbers are for reference only. POOLPURE stands as an independent brand.