Flat gasket/o-ring for Intellichlor connection?

[capp35]

Online for the IC40 seems to be all round o-rings. The connection on mine uses more of a flat rubber gasket/washer style.
Any idea on part number or where to get?
Thanks

 

[PoolStored]

521147

 

[capp35]

521147

Thank you, sir, but that is the round one I was talking about.
My connections use a flat O-ring/gasket that’s about an eighth of an inch wide.