The Unicel C-4440 is a 4000 Series 40 sq. ft. replacement filter cartridge built for Sundance Spas filtration systems. Featuring 158 precision-folded pleats of 4 oz. Reemay 2040 polyester media across a 16 3/4" profile, it delivers thorough debris capture and sustained water clarity between cleanings. The castle-style closed top cap and open bottom seat securely on your spa's standpipe — no guesswork, no adapters. ⚠️ IMPORTANT: Some Sundance Spa Models Use Two Filter Cartridges Certain Sundance Spas are equipped with a dual-filter system that requires two separate cartridges — this C-4440 (replaces Sundance 6540-495) and a second filter cartridge (Sundance 6540-497). If your spa uses both part numbers, you will need to order both filters for a complete service. The companion filter is the Unicel C-4305. Check your owner's manual or existing cartridges for part numbers before ordering. Specifications Filter Area 40 sq. ft. Length 16 3/4" Outer Diameter 4 5/8" Top Inner Diameter N/A (closed castle cap) Bottom Inner Diameter 2 1/16" Material 4 oz. Reemay 2040 Pleat Count 158 Top Cap: castle Bottom Cap: open Fits into: OEM Brand Product Name Part Number Notes Sundance Spas — 6540-495 Primary filter cartridge. Some models also require 6540-497 (see callout above). (This is not an exhaustive list.) Pro Tip: Before ordering, measure your existing cartridge end-cap to end-cap (16 3/4") and confirm the outer diameter (4 5/8") and top cap style (closed castle). Sundance filtration configurations vary by model year — verifying by OEM part number 6540-495 is the most reliable way to confirm fitment. Also known as: C4440
