A high school classmate was killed riding his bike this spring. The driver was an elderly man who simply didn't see him as they were both heading east into the rising sun. The tragedy prompted me to start looking for a brighter taillight that is very visible during the daytime hours.
Most of my biking is mountain bike single track in the late afternoon, early evening after work. I also road bike often enough to warrant a daytime rear blinker.
The CL05 is very bright, very visible in the daytime. It has several modes to choose from: 3 solids of varying intensity, and approximately 4 blink modes to choose from, each with a different pattern. The unit is rechargable and the rubber strap connection to the bike seems durable and allows for a tool free installation and its easy to either unclip the light from the mount or just as easily remove the whole thing to use on another bike or to take with you when parked in public to prevent theft. As I said, very easy, tool free mounting.
One cool feature is the auto mode change. When riding at night and you've selected a solid mode, the CL05, is equipped with a light sensor, so when a car is approaching from behind, the CL05 can detect the cars headlights and switch to a bright flashing mode. This helps get you noticed well before the car is upon you. This mode must be turned on (single button press) and is designed to be used at night (it's a light sensor, so if it's switched on during the day, the flash mode stops and starts randomly and may not turn on appropriately when traffic is approaching. Works perfectly at night, however. It's a good feature.
I gave it 5 stars for brightness, variety of flash modes and the nighttime traffic detection feature, and tool free install. Also can be used to clip on a helmet or back pack, so points for versatility.