The idea of a combined white and red light in one unit might seem like a good idea, until you fit it to a bike.
If you put it on your seatpost, you end up with a red light only visible from one side, and a white light which illuminates the back of your leg. If you put it on your bars, then you get a white light in front, and you light yourself up red. But... If you put it on the side of your helmet... Ah ha! You would need two of them, but it's not a bad idea, and adds a lot of visibility at the expense of looking a bit like a Christmas tree. The only problem is, you have to pay £17.99 two times to do both sides of your helmet. A slightly bonkers product, but one that we couldn't help but try to find a use for purely because it exists.