RVSuppliesPlus@RVSuppliesPlus.com
This O-ring seals a static joint on the pump assembly. It is EPDM, an elastomer commonly chosen for water and mild-chemical service. Like any elastomer seal, it hardens and loses sealing ability with age and heat cycling, and should be replaced whenever the joint it seals is opened.
Always match by the MP Pumps part number 36911 listed on your equipment parts diagram, since dimensions and material vary across the MP Pumps lineup even for parts with the same common name.
Not sure this is the right part? Send us a picture of your Pump Plate to https://www.clrmarine.com/Contact-Us and the CLR Marine team will confirm the correct o-ring.