basically - they need to either have opening for the treadle belt, or the flywheel has to hang over the base of the machine. And they need to have a belt grove in the flywheel. I was looking and I've got several that could be put on a treadle, for the zigzag, my new Necchi and the 401G have holes in the bed, and the Brother's flywheel sticks out enough that the end of the machine would not interfere with a treadle belt.