Bright light, automatically turns on. The only thing you need to do is remember to charge it. For charging It fits any place you can plug a USB plug into. On my laptop it more sits in the USB jack but it charged just fine. I am sure it will not run for an entire century ride but works good on my rides so far. Easily attaches to the bike. Easily removed for washing the bike, would be very easily swapped between bikes for those who have more than one. The light detaches from the mount for charging by pushing in and twisting. It is good to have a day time running light function. As another reviewer suggested, I put a small piece of electrical tape across the top of the headlight so it isn't shinning up. I do some commuting, 20 miles each way, most of my other rides are 15-40 miles, I live in a rural county, living in one town and working in another.
I love these lights. Easy to use, bright, functions exactly as stated. My one gripe is the front light, I find the light that comes back to my eyeballs while riding to be quite annoying, even in the daylight. I solved the issue by placing a small piece of black electrical tape over the top of the light. Problem solved. Hopefully, L&M will solve this issue on the next generation.
These lights were to last run up to 6 hours. About 3 hours into the ride, the taillight was off. The head light lasted 4 hours but disappointed that the more important light did not do well. I have had great experiences with Light and Motion products in the past so to say I was surprised and disappointed is a little understatement. The way it changes and the ease of loading it off and on the bike mount are really great, just wish it would last longer. Last 5 hours and this is an easy 5 star product.