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C-4637 spa filter equivalents
Part number C-4637 appears in 1 cross-reference row below. Each row lists the OEM, Unicel and Pleatco numbers that the source documents treat as interchangeable, plus the cartridge size so you can confirm against your old filter.
The same numbers, on one page, are in the cross-reference lookup. A schedule for this part number, and the buy link, are on the replacement schedule and reorder page. Published intervals by brand are in the replace and clean calculator.
Freedom Spas C-4637 cartridge, 4-15/16" (125 mm) × 13-5/16" (338 mm), 37 sq ft. Unicel C-4637, Pleatco PRB37-IN-4.
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| OEM | |
|---|---|
| Unicel | C-4637 |
| Pleatco | PRB37-IN-4 |
| Filbur | FC-2380 |
| Size | 4-15/16" (125 mm) × 13-5/16" (338 mm), 37 sq ft |
Sources
- Unicel 2026 Replacement Guide: Freedom Spas line, PDF p.35 (printed p.31): Concord, Patriot, Ambassador, Executive = C-4637, 37 sq ft; spec table PDF p.9 (printed p.5): 158 pleats, 2-1/8" open, upgrade of C-4326 and C-4625, application line does not name Freedom (PDF)
- Filbur Catalog & Reference Guide: Freedom Spas section PDF p.18 (printed p.35): FC-2380, Rainbow Dynamic 37, PRB37-IN-4, C-4637, 37 sq ft. No Concord names (PDF)
Not in sources: Concord, Patriot, Ambassador and Executive are Unicel's Freedom list only. Spec-table applications and Filbur do not use those names. The following C-4950 row, not this one, carries the 1993 note. No Freedom OEM number..
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