http://www.aliexpress.com/...tail/1461897105.html 2x Cree XP-E red leds. You can set it to have both constantly on or one on and the other flashing.
Needs an external 8.4v battery like high powered headlights. I have it and my headlight hooked up to an eight cell brick in a saddle bag with my patch kit, levers, and CO2 cartridges.
battery:
http://www.ebay.com/...e=STRK%3AMEBIDX%3AIT headlight:
http://www.ebay.com/...e=STRK%3AMEBIDX%3AIT I commute around an hour each way, just after dawn in the morning and well after dark at night, with the mileage split between unlit bike paths and in urban traffic.
This light set up is amazing! Better than anything else I've experienced.
Speaking to the tail light specifically, the angle of my seat tube points it down a bit so it creates a giant red ellipse, around 8' across, behind you on the ground. Very noticeable to overtaking traffic. The light itself is still super visible even with the angle. It is the brightest tail light I could find that could be bought. The only way to get a brighter one is to make your own with three or more XP-E emitters. There are only a couple of annoyances: it could be a bit smaller, and once you turn it on the only way to turn it off is to unplug from the battery. When you plug it into the battery, the rear light flashes then stays off until you switch it on. After turning it on, pressing the button just cycles it between two-on and one-on-one-flash.
The headlight is brighter than some car lights, is quite small, and has a three led power meter on the backside. It switches between off-low-med-high. I kinda wish it had a strobe function, but that is the only annoyance I have with it.
With the eight cell pack, headlight on high, and tail light set to one-on-one-flash, I can go almost two hours before the power meter drops one led. I haven't done a full rundown test yet because the headlight gets pretty damn hot if it doesn't have airflow around it and I'd rather not ruin the light.