This is the available filter as the PWW50P3-M is obsolete.
Here is an alternative - https://dynastyspasparts.com/great-barrier-8550-filter/
Description: Cartridge
Diameter: 6"
Length: 7-5/8"
Top: Posigrip
Bottom: 1-1/2" SAE
Related Products:
6CH-940
OC6-940
PA-AP60401
PA-6940