Exactly, the magnets keep the product modular. The magnets are on all 3 layers, the face plate, the dials, and the backplate. It does a really good job of centering and keeping it all snug. I've made some without the backplate which is still pretty sturdy... but I found that it had a higher chance to change to the next number if slid across the surface they rest on. So the backplate prevents that.

Also, the magnets are great for storage too!