This is my primary light for pretty much everything. I did a week of vertical caving this year and this light stayed bright and reliable the entire time. I have done water passages and fully submerged with no problems. Not exactly lightweight... (if that is what you are looking for)

Although the battery pack is significanly larger, this puts out more light for a longer period of time than the "pro". Great product. I had a few issues with my first one. The headband and the articulation point for the light broke. I think it was a fluke, as I haven't any problems or additions troubles. I appreciate the overall construction: h20 seal on battery pack and simple mechanical fastener of the light articulation point. Essence: well built (att. to detail), great light output. (far best I've ever seen) Great customer service. Highly recommended. Get the pro if weight/size and battery duration is of great concern. Get the reg if looking for a longer lasting (batt power) bomber light. Downside: the buttons are a bit troubling with cold fingers or gloves.
I have one of each=STOKED

This is a good caving headlamp that I have taken on many trips. It seems to be pretty water and dust resistant and takes abuse fairly well. I also have a Petzl Myo RXP that doesn't seem nearly as heavy duty. I walked into a basalt roof and hit the front of the lens very hard, and it came out with a hairline crack.

I have used this lamp for a few years now and love the brightness. The highest setting really lights up the trail. This is a pretty comfortable light for its size. It can be bouncy for running thus leading to motion sickness for some. Without question this light is a battery eater. On the max setting expect no more than 2 hours. I always run with a hand held as well and save the bightest settings for technical downhills. Overall a great headlamp, but for running I would check out the BD and Petzl offerings.

this has to be one of the brightest headlamps around, I have been useing mine for 7-8 years nowe and its still going though the hinge has cracked and broken as well as chips in the the top casing. it also gets hot on the head but not a bad lamp!

I have had dozens of head lamps over the last four years working for the government in civil service, and they all sucked, petzl, pelican they prob all have their places (cooking around a campfire) but making the step and buying the Princeton Tec Apex out of my own pocket was a good move, I use it in a highly industrial environment, wearing it while grinding with it on submarines, to crawling the tanks and bowels of the subs and the worst environment I think can be thrown at it, pressure washing in tanks with 130 degree water, the Apex shows me where Im working like no other can! Go Princeton Tec, I'd like to see you try and out-do yourself!!