Got one of these strapped on my helmet:
https://www.walmart.com/ip/Bushnell-...eries/55505076

Incredibly dumb design, IMO; there's no battery indicator, and if there's not enough power for high, it just shuts off rather than going to low. Made worse by the fact that it's press once for high and again for low, so you can't even get to low when the batteries are "weak." If you double click it fast enough, you can usually get through to low eventually, and I've had it work fine on low for >30 minutes when high wouldn't work, so it's clearly not that near dead at that point either.

That said, with fresh batteries, I'm comfortable up to about 12mph with just it, so it is a handy backup for my big 4x18650 headlight as a "see" light on the commute. Also very handy for watching what's not right in front of me when weaving between potholes, or for "sweeping" cars to make it more likely that I have a driver's attention.
Red is good for setting up camp or doing closeup tasks where a white light can be glaring, and blue is good for spotting fluorescent trail markers and such.