It's for cars so it won't be waterproof, although it's right behind the screen and will stay relatively dry. I won't be surprised if it only lasts a few months, considering the price,no big deal.
It's just one of those things that are nice to tincker around with, you know, you are looking at the bike, and thinking; what more can I screw on to it, what can I buy to improve it even further... it's a hobby!
ps: link ebay shoud work now