Spa Filter Baleen: AK-8021, OEM: WC108-59S2x, Pleatco: PSR135-4 , Unicel: UHD-SR135 , Filbur: FC-2560, Diameter: 8-11/16", Length: 34-1/2"

Filter Specifications:

• Square Footage:
• Media/Thickness: 4
• Diameter: 8-11/16"
• Length: 34-1/2"
• Top: 4-3/16" Hole
• Bottom: 4-3/16" Hole w/ concentric

Equivalent to:

• Pleatco: PSR135-4
• Unicel: UHD- SR135
• Filbur: FC-2560
• OEM: WC108-59S2x

This Filter Fits The Following Brands:

Filter Glossary

As you can see in this graphic, when looking at a filter's threads from the side the difference is very obvious. Standard, sometimes called "MPT" or "Male Pipe" threads are smaller and have a higher number of threads than the S.A.E. style. The S.A.E. threads are large and are square in nature almost resembling a child's toy.

• MPT: Male Pipe Thread
• FPT: Female Pipe Thread

How to measure a hot tub filter references:

Spa Care Center or Pool Care Center