That mystery stainless steel inner tube is an exhaust donut (probably)


A week ago, I blogged about the mystery stainless steel tube I saw during a recent trip to Maine. I used the item to demonstrate the challenge of “visual search” based on shapes and colors. Visual search is a big deal, even Google has recently purchased for its visual search technology. As I mentioned in the previous post, I tried sites like, TinEye and idee’s BYO Image Search Lab, among others, in my initial search. However, I didn’t have the vocabulary to help them out. “Round” “metal” “tube” — those words together can bring some interesting responses, believe me.

Next time, I’ll use E-Z Fynd.

As I figured it would happen, the mystery was not solved by a search engine, but by the crowd — specifically the crowd that visits the website Book of Joe. As Joe has “what is this?” quizzes from time-to-time, I reached out to him for his advice and the wisdom of those who keep up with the stuff he discovers.

After a couple of promising, but wrong, early guesses, a reader suggested it is an exhaust donut used in the creation of custom exhaust systems. If you compare what the original item looks like with this parts page I found via Google, it sure looks identical to me.

Unless, that is, you have a better guess.