Cannondaleriders

I changed the oil this weekend, and the large o-ring came up missing, resulting in an oil leak. Is this something that I can get at a decent hardware store?

Sure bring cover along and fit one to it.

My parts catalog says it's a 2-033 O-ring I dunno what the "2" stands for, but I found several o-ring suppliers with -033 O-rings in thier catalog, all of them the same size. I'll try to dig one of those up.