Need o-ring size for hose on B/S pwr washer

I have a Brute power washer model #020577. This is made by Briggs and Stratton. The o-ring in the hose end that attaches to the gun is gone and I need to replace it. I do not want to buy the kit, I want to get the o-ring size and replace it. The part number for the hose is 316465GS. The o-ring kit (which I do not want to buy) is part # 705001 (I think). The gun is part #704622. Anyone know the o-ring size? I found it once but I can not find it again. I seem to remember it being 3mm x 3/8 inch, but I don't know if this is correct for sure now.