Over the summer on the way home from Loonie races I threw a Bontrager Flare R Tail Light onto my bag for the ride home.
It is designed very well and was a snap to put onto your seatpost with the moulded rubber strap. The strap has a quick dis/connect so that you can pull it off in a snap.
The Flare R Tail Light has two different daytime & night time settings, and two output settings, one at 65 lumens and one at 35 lumens. Trek claims that 65 lumens makes the Flare R visible for up to 2km away, day or night. And I don't disagree with it, it puts out some serious power.
At full strength it will last for 4.25 hours on flashing, 4.5 hours on steady, and on night setting it will last4 for 23 hours on flashing setting or 21 hours on steady output.
I think I only had to charge it a couple times over the summer, it truly does last quite a while. Charging is done with a mini USB charge cord that is included and easily connects to any computer or charing brick you have laying around.
A light isn't something that is always top of mind, but it sure does make life a lot safer when it starts to get darker out.
Price: $59.99 usd