Pleatco:PDM25P4, PTL18P4-4| Unicel: 4CH-21 | Filbur: FC-0136, FC-0121 Diameter: 4 5/8'' Length: 8'' Top: Handle Bottom: 1 1/2'' MPT Threaded Filter Area: 20 sq ft Filter Material: Pleatco Advanced (4 oz/yard) Note: 4 oz filtration material is 33% thicker than the standard 3 oz. As a result it will last longer and filter more thoroughly. Alternate Filter Names: 20245-238 | SD-00845 | SD-00821 | SD-00838 | 17-175-1025 | 090164187006 | PTL18P | PTL 18 | PSN50 W/ PAD AD | PTL18 W/ PAD | PVT-25N | PA17 (PAD OPT) | PA13 | PSI18 | PTL18P-4 Used in pools / spas made by: Alcove | Atera | DM Industries | Dream Maker Spas | Maax Spas of AZ | Pageant Spas | Saratoga Spas | Vita Spas and other manufacturers