Have a few of them just for safety. The ones I have are single bulbs and cannot be on the same connection with others. Not sure how to say it but lone bulb, lone on off switch. In any case I have one in my kitchen. One over my garage door and one in my hall bathroom. They do work. Fortunately I have needed them only once and I have had them over 5 years.
you have to recharge them, every now and then too. we haven't needed ours, yet. Mine have the little add'l scr#w top that has a hook and on/off switch. Mine were a tsv, maybe a 1 1/2 year ago.