Just got this light for $12 from Amazon. I have a Surly rack so I had to unscrew the clip & then attach the light with one bolt that goes into the back of the light. Took five minutes in all. It's an ideal rack light because it's very bright, takes AA batteries that are long lasting, has two blinking modes & a large reflector. It's basically DToplight plus two blinking modes at less than half the price. Highly recommended.