Ok Verm, sorry it took so long...
small o ring: 3/8" ID x 1/2" OD x 1/16 rubber diameter (2418T118 012)
larger o ring: 1/2" id x 5/8" OD x 1/16 rubber diameter (2418T12 014)
If you can't find them locally, Mike orders them from McMaster-Carr, the order numbers in parentheses above.