One LED, powered by three AAA batteries, does a remarkable job of providing usable light for walking and reading. Interestingly, the EOS has a rather sophisticated light selection system: you may choose three levels of solid light brightness and a blinking mode by repeatedly pressing the detent switch atop the unit. Regardless of your choice, after three seconds without a change (you've presumably selected the mode you wish) one more press turns the light off. A very nice touch; thoughtful.
The housing is attached to the comfortable handband with a hinge, making it very easy to read bedtime books to the kids (or adjust the light to a map or trail). The light color is a pleasant white, bringing out the illustrations in childrens books and the different vegetation in the garden.
Like the other Princeton Tec lights we've reviewed, the EOS is rugged enough for the kids to run roughshod over it, throw it, and smash it with their other toys. It was none the worse for the wear, and the virtually unbreakable LED didn't let us down.
If you need more light, and are willing to tolerate a back-of-the-head battery compartment (still pretty comfortable) and sightly more weight, you might want to consider the Princeton Tec Yukon HL headlamp.
Conclusion
The Princeton Tec EOS LED headlamp is rugged, comfortable, small, and usable. The hardy detent didn't turn on by accident in my cramped pack (something other, lesser headlamps have frequently done). It does its job very well, with neither any superfluous silliness nor any missing features. We give it an unqualified recommendation.
The EOS is the smaller of the two Princeton Tec LED headlamps we're reviewing.
