Three types of light action plus the accelerometer that senses when slowing and changes the pattern to a full, bright red. Charges well, works well. My complaint is neither of the 2 included rubber anchors fit an aero seat post. When I contacted Cat Eye I was directed to purchase an accessory pack for the light. Are you kidding me? It is an easy fix I had some other stretch O-rings and used one of those, but with all the competition out there I cannot believe Cat Eye would not include an aero anchor (which is just an o-ring) or at least send you one when you inquire. A great light but a strange philosophy of customer service and satisfaction.
I have used this several times. The light has very eye-catching modes from straight flash to strobe. When you decelerate the mode changes to a very bright, solid red. It does work. I notice I get a wider berth from vehicles when I am using versus not - it may must catch their attention a bit earlier. I now will not ride without a tail light given some serious collisions in our area due to inattentive motorists. The varying strobe setting is my favorite as I feel it is more what would catch a motorist's eye. If you have an aero seat post note that the unit does not come with a band that will fit your post. I found a larger o-ring wth some stretch that works. You can purchase an aero 'kit' for this unit that includes a different rubber mount. I found the one on the unit works, it just needs a bigger band. In this day and age of aero bikes I wonder why a company that produces such quality items would not include this, but there is a workaround if you don't want to pay the extra.