Tom or Alma...I may need an O-Ring next change (or even tomorrow if it continues to leak after redoing it with plenty lube, i think it was tightened too much & flattened) for the expansion housing.  The one ring in your store is reasonably priced however add $7 for shipping.  Is that the correct ring for the expansion housing?  Can a compatible item be purchased locally or elsewhere?  Thanks!

Terry Premru Hi Terry, Yes that O ring is the correct one and unfortunately, there is no cheaper way to ship this. We send it in a padded envelope via Priority Mail (USPS). We've had customers who have tried buying O rings at Home Depot or Lowes but all of them ended up leaking. The size and thickness needs to be exact for a proper seal.

Will that Oring fit the same housings for the FS75 filter set?

Terry Premru Yes.

Alma thanks then i will follow link to buy a couple!