On its highest setting you'll be lucky to get 45 mins of light. Probably less. But wait there's more... when you sync the light up to your Garmin cycling computer using the smart technology be prepared to have the cycling computer completely freeze up and require a factory reset. That's right..... you'll need to re-program all your screens, personal data, etc... On the plus side, it looks nice.
I have the light mounted to my helmet using a GoPro system. The light works well and the battery life has been very good. When connected to a Garmin head unit, the light will turn onoff automatically and will get brighter with speed. Light coverage is good for the trails I am riding. I generally have a light on the bars plus this one on the helmet.
Easy to attach to the Garmin computer dual mount without taking up space on the handlebars. Also, very easy to turn on andor adjust mode while riding. It has a reasonable operating time before required recharging. It is also water-resistant as I found out when I was caught in a rainstorm. The headlight continued to function properly while my taillight (another brand) was not able to handle the deluge. However, the Varia is more expensive than other headlights of similar wattage.
Garmin makes pretty good products and their UT800 is no different. Its bluetooth compatible and you can hook it up to your existing Garmin Edge device for connectivity. Its baytery life is pretty good lasting around a couple of hours on the solid beam section. I have this parked with the Garmin Varia and they work well with one another. Hopefully their next iteration the light will be better.
The road bike version of Varia 800 comes with dual holder for garmin gps and light. Easy to assemble and has settings for night riding to bright flashing for daytime. My only complaint and its not against the light so much but the blue tooth is interfering with my garmin 810. Its not supposed to work with the 810 but its causing pauseresume issues as its tryng to connect.