A bit more info for John and anyone else interested.
The Oldham DL 16 is designed as a coal mine safety lamp, and as such there are better choices out there for recreational exploration of metal mines. I have to give mention of Stenlights, Little Monkeys, Vipers, etc as well as my own offerings.
There are also the Oldham retrofit conversions such as Mr Mikes.
If you look at the Oldham LED headset you will see a metal ring which is a component of the heatsink system. This is of cast nickel and no doubt is reflected in the price of the lamp. Aluminium is not part of its construction in order to comply with coal mine safety certification.
The lamp is notable for its very narrow beam. The emitter used is of an early type that gives about 90 lumens for a consumption of about 4 watts. My EcoStar will give 168 lumens for a consumption of 1.68 watts so hardly needs much of a battery. Similar efficiency is available from many other lamps that use the latest Cree XM-L emitters.
For fans of belt mount, I do one of these which is the same size as Trigon helmet pack and gives 24 hours light on the standard setting.
My avatar is a poor likeness.