When sknhgy suggested that a new red LED torch from Ultrafire might make a good rear light it was something of a no brainer for me, especially as I already had 18650s and a nice charger.

Having already bought some Ultrafire torches I knew that they are very good quality and work very well, and when I discovered that the red LED torch was being retailed for less than $10 - well.... it would be rude not to buy one, wouldn't it ?



Ultrafire WF-501B Philips Luxeon K2 Red LED Flashlight

Here's some specs: 134mm long (about 5 1/4"), 136g (4.8 oz) including battery.

It looked like mounting might be a bit tricky, until I tried the Fenix mount, which was the first mount I bought and had never found a use for.



Fenix Flashlight Bike Mount

As with the other Ultrafire torches I own build quality is great and light output is quite surprising.

There's a lot more info here: Red LED Ultrafire torch

One other thing, it will run for 4 hours on one 18650.