Holy moly, do NOT look directly at them when you're going to test them out for the first time. In fact, when putting the batteries in make sure you're not on an overly reflective or white surface and keep it pointed away from you. These suckers are BRIGHT!And for taking 3 AAA batteries each, they last quite some time! I used mine during a Hurricane to navigate my house - I even fell asleep with one on and to my surprise it was on when I woke up around 5 hours later and was BARELY dimmer.Also, where ever you decide to stick them YOU BETTER BE SURE THAT'S WHERE YOU WANT IT. You might be able to move them within a few seconds of sticking them up - but I have one in a cabinet that fell down, I left it where it fell because it was useful where it was -- until the cabinet got more full. I went to pull it up and it has ADHERED to the bottom of that cabinet. It's going to either leave behind the sticky pad or some damaged plastic when I finally get it off of there. Currently struggling to even pull it off of there. Lol.But yeah, strong sticky pads on the back - super bright LEDs and pretty decent battery life ESPECIALLY if you're only using them for short bursts at a time. Since purchasing them, I have not had to change the batteries in ANY of them. I keep them around the house for emergencies and 2 in cabinets to be able to find stuff in them since they're black plastic. But yeah, you will be able to see an entire room when your power goes out [not as good necessarily as an overhead light or a lamp can light it up, but you're not going to trip over anything and you'll be able to safely navigate the room!]And if you live somewhere the power goes out randomly but regularly, I highly recommend you mount one near your shower/tub so if you lose power in the shower you can tap it and see yourself to safety [or at least finish your shower safely].