On a good day, a company creates a successful product. On a great day, it invents a new category of product. Petzl claims to have done both, with its all-new NAO headlamp. The headlamp kicks off a category that the company calls "Reactive Lighting."

According to the rep that we spoke to, the NAO will become Petzl's brightest headlamp, offering up to 355 lumens. It isn't just powerful; it's smart. Just above its two LEDs, the NAO has a sensor that measures ambient light and adjusts the beam strength and pattern to the light conditions, aiming to give you the optimal amount of light while conserving battery power.

If you're looking straight ahead on a dark, moonless night, the NAO will deliver a high-power, long-distance beam. On the other hand, if you're reading a book, it will cast a wide, low-power beam. Not only do you get the exact amount and type of light you need, but you don't have to fiddle around with adjustments to get it.

Reactive Lighting replaces what Petzl defines as the two existing light modes in the headlamp market: declining mode and constant mode. The former maximizes a headlamp's burn time by gradually lowering the amount of light output. Because light output decreases over time, declining-mode devices could very well leave you with the least amount of light in the darkest conditions. Constant mode offers a constant light output but only runs for a short amount of time. Reactive Lighting attempts to merge these two strategies and give you the best combination of light strength and burn time.

Of course, some people and activities demand a consistent light stream. For them, the NAO offers a steady beam at the flick of a switch. With OS by Petzl software, which is available for download on Petzl's website, NAO owners can customize light settings, creating up to four activity profiles with five different lighting levels each. So if you find that the NAO's reactive output isn't quite right for your needs, you can fine-tune it to suit your preferences. Profiles can include light settings specific to activities like trail running, camping and mountain biking.

The NAO's dual-strand Zephyr headband looks a little awkward at first, but it provides a simple tightening mechanism that you can adjust with one pull with the NAO on your head. When not in use, you can tighten it all the way down to quickly minimize its size.

The NAO uses a rechargeable lithium-ion battery that the company calls the ACCU NAO. This pack can be recharged up to 300 times via USB connection. In an emergency - say if the lithium ion battery dies while you're out in the wilderness - you can use use two AAA batteries to give you a low-power beam.

Petzl plans to launch the Nao in July for US$175. You can get more information on the NAO's web page.

The Petzl video below provides a visual introduction to the concept of reactive lighting.