Source for oval stove pipe or adaptter

[zzvyb6]

I wrapped a string around the oval and it's about 22 inches. Divide by 3.14159263 and you get a 7" diameter pipe. I ordered a 7" oval to 7" round adapter. ($15 ebay + shipping) . Came FedEx the next day. Fits perfectly. Now I'm waiting for a 7" to 8" adapter to cap off the pipe with an 8" vent cap I got from a garage sale.