Joule comes with a small clip that works fine with all pots/pans and smaller Cambro/Lexan containers. No need for the magnet -- though it's there if you need it! The Big Clip is only necessary if you're going to cook in a vessel that has a huge lip like a cooler or the "classic sous vide" 12X18X9 Cambro containers. Joule is so small that its small size allowed me to scale down my cooking vessels and use much, much less water for most of my cooks. It's so small that you can run it in a mason jar. The size of Joule was, and remains, the big attraction to me. I almost never use my huge Cambro anymore.
I've been somehow able to resist buying Modernist Cuisine at its best price ever.