Prosself contained no batteries hardwearingconsnot as bright as green or some of the others quick service great product

If you want something you can pick out at a distance then go for green or blue if you just want to be discrete and be able to pick something out from your hands in the dark such as a particular key on a keyring from example then this will do the job

Would recommend buying from nite tritium gadget keyring glowring new colours