It's 3" x 3 " x 1 1/4" tall.
The plastic X is necessary to keep the magnets from pulling in to each other. It's a bad idea to install them individually.
If one falls loose, there's no telling where it will end up. When not held apart by the brace, they tend to pull in towards each other and will come unattached from the inside of your double bass.
We're working on new ideas for X-braces that can fit through f-holes and we hope to have something available soon.
That's one of the problems we're hoping to solve soon!
I agree completely, Jim.
As unfortunate as it is, our current TWA will not work with ALL guitars.
If you're absolutely set on using it, then we recommend the painters tape to hold it in place.