The energy fields of our large units, like the E4004 and E9004, can better function optimally when they are hung at the suggested height of between 15-20cm / 6-8” above the floor. A practical benefit is that it cannot get knocked over as easily either.
Portable units like the E704 do not have a feature to hang them up. They just stand on a desk, on the floor, go in your bag or you can take them with you in the car.