I use the q40s for commercial diving and darkwater megalodon teeth. These lights are super bright for their size. They are very slim and lightweight now which allows for more options, adding multiple lights with the luxury of not taking up much space. They are durable, I've used them in the mud, ice and hot cars, still no problems. The battery life is great, I like the large push button on the back. I've been getting over 12 hours on one set of batteries lately. These are the best lights anywhere close to their price range right now. I definitely recommend them.