I don't have a high shelf. Who would I get to install them? Do I plug them in or use a battery?They have basic ones for like $10 at Walmart. They don't need to be fancy . And the new ones don't go off for no reason as much as the old ones did. I'm sure they'll work, or someone would have sued the company already. And you can just put them on a high shelf , you don't have to mount them on the ceiling. Better than nothing!