Outside diameter 3.75", thickness 3/16". Marek #1028 Lake Ontario On Fri, Sep 30, 2016 at 11:49 AM, Descher, Chris <cdescher at cedtulsa.com> wrote: > Anyone know the size of the o-rings that go on the water tanks? Mine are > dry and cracked and need to be replaced. > > > > Chris Descher >