Pump Housing Question

[Boat Hack]

I am changing the oil seals and water pump housing on my 2001 f100. The new pump housing came with a split metal ring. What is that for?

[fairdeal]

its just an improvement to the design
after the seals go in,
the circlip goes into the groove to 'retain' them

[Boat Hack]

Thank you! I couldn't find it in the exploded diagram. Probably shows up in a later year.