Sizes in o-rings and gaskets can be misleading
Our measurements may not be exact but close
The flat gaskets work best when used with the old o-ring still in place.
The flat gaskets work on both heater and pump unions.
The O-ring / gaskets are flat gaskets with half an o-ring molded on one side to hold them in place better.
The extra thick 2 gasket fills the gap on heater plumbing that is a bit off

We can mail these out via first class for a few dollars shipping
Part # | Description

Standard O-rings
90-423-1000 | 1.5 in O-ring | 2 OD, 1-3/4 ID
90-423-1005 | 2 in O-ring | 2-5/8 OD | 2-3/8 ID
90-423-1275 | 3 in O-ring | 3-1/4 OD | 3 ID

Flat Gaskets
90-423-1001 | 1.5 in gasket | 2-5/16 OD | 1-1/2 ID
90-423-1006 | 2 in gasket | 3 OD | 2-1/8 ID
90-423-1009 | 2 in x 1/4 in thick gasket |see photo

Gasket / O-ring Combo
90-423-1002 | 1-1/2 in O-ring /gasket | see photo for size
90-423-1007 | 2 in O-ring /gasket | see photo
90-423-1008 | 3 in O-ring /gasket | see photo