This headlamp emits 540 lumens, good enough to reach 172 meters while using 2 CR123A batteries.
It also comes with 3 programs: High/Medium/Low, High only, and Low/Medium/High
On high it runs 1.75 hours, medium(95 lumens) runs 8 hours, low(18 lumens) runs 36 hours.
http://www.streamlight.com/en-us/product/product.html?pid=294
From: Streamlight