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Review title: Pretty cool
Product review: It's not quite "invisible", it shows up on black plastic about the same way that a black permanent marker reflects light on black plastic that lets you read it. I wrote on my computer and the markings are clearly visible in the way that really thick water spots are and you have to be in near darkness for it to show up with the key chain. Also doesn't really work well on white backgrounds since black light makes white objects glow to. The little key chain is pretty sweet though and you can write on just about anything that you could use a permanent marker on. Although I took the batteries out and tried to put them back in and for the life of me I can't get the light to work anymore.
