Stomberg Carb O ring dimensions

[Stu Booth]

First of all this is a great resource. I wish I had more time to devote to cars right now but....Anyway, the oil is running through the carbs pretty quickly now and its time to replace the o-rings. Does anyone have the dimensions of the small o ring that fits the top carb? My model is a '71 sprint emission. Are the ones available at the hardward store any better, worse or the same quality as the one you get in a carb repair kit? Thanks Stu