The IXXI (ick-see!?) sounds like a disease you get when you eat to much carnival food. But the Gothic lords of lux are as bad at naming things as they are good at coming up with great lights. This is a tiny, rechargeable tail light that you can strap anywhere that things can be strapped. Seatpost, pinkie finger, chainstay, rack stay. It’s bright, has a long burn time, and importantly, has a solid red beam. Flashing beams are not only obnoxious to ride behind, they’re also bad at letting drivers judge distance to a cyclist. A solid beam gets bigger or smaller with distance. Hard to judge with the disco rave flash pattern that lots of lights produce. This light is small and feathery. Stick it on your fast bike, or use it as an additional light to bolster your dynamo tail light. Bright enough to be your main light, but a fine back up too, cause of the size thing.