Make sure you know your size
I had the exact opposite of the last guy. I needed this lid but bought the 10 inch first. The 10 1/2 inch is what I needed for my stock pots. If you are not sure give All-Clad a call.
NOT for the pan
I measured my frying pan and thought sure this was the right lid, but what I needed was to 10-incher. This is for some kind of pot or something.