Originally Posted by 2manybikes

I just got in a couple of white ones for the front. They came from DealExtreme and were less that $4.00. They had different packaging. The package says "steady 50 hours, Flash 150 hrs". I tested the red one for about 16 hours and got tired of testing it. I'll assume the 150 hours is to when it goes dark. So a very conservative guess, based on my testing, would be possibly, 50 hours on flashing? say 25 hrs flashing, and then it's weaker. I bought 20 cr2032 batteries, they were $0.55 each. The light takes two batteries. For me if I'm riding a lot, I might do 5 hours a week in the dark on average.
With my estimates all leaning a little to the worst possible battery life- 25 hrs / 5 hrs a week = 5 weeks for two Batteries That cost me $1.10.

Making all the estimates way worse than what they claim, this will cost me $1.10 for 5 weeks. Realistically probably longer run time. I'm going to ride with them and see how they hold up. The packaging says "waterproof". At this point they seem to be cheap, bright, good run time, and lightweight. The front or back can be used as a flashlight to see something on the bike, or riding walking speed in an emergency. I would expect steady to the chew up the batteries pretty fast ??

They may have a quality problem, down the road. Pun intended. If they don't break I like them. At the very least, a good thing to have in your bag on a night ride.