I could take one if I had never dropped my camera on the concrete floor.
Dont work so good now.
Its a black box, about 4in. by 2in. and an inch thick. It just has an electrical contact in it and a plug in on the back. A mono line hangs from the switch with a large fishing bobber on the end. I have a small weight on the bobber to keep it sraight but not enough to pull it down.
It just opens and closes the contact with the rise & fall of the water. I have been using it of and on, {like my sump}, for about 5 years.