Spa Filter Baleen: AK-5018, OEM: N/A, Pleatco: PMS20-4 , Unicel: C-6620 , Filbur: FC-3840, Diameter: 6-1/4", Length: 8"

Filter Specifications:

• Square Footage: 20 sq. ft.
• Media/Thickness: 4
• Diameter: 6-1/4"
• Length: 8"
• Top: 2-5/8" Hole
• Bottom: 2-5/8" Hole

Equivalent to:

• Pleatco: PMS20-4
• Unicel: C-6620
• Filbur: FC-3840
• OEM:

This Filter Fits The Following Brands:

Muskin A3821, Sears

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