Just running one of the 5W Luxeon lamps (3W also available) on this LED system gives good coverage and depth for a decent pace on technical trails. Using both allows a broader spread or more infill to reduce 'overshadowing' from following lights. Slightly 'yellower' light than the USE and Hope reduces clarity slightly, but there's less glare in damp conditions.
The CNC housings are super neat with O rings looping round into small slots for secure mounting on all bars. Illuminated push switches give two outputs for juggling run times, too.
The small Li-Ion cell straps on anywhere, recharges fast but still runs long enough for serious nocturnal adventures. Battery magazines for rechargeable or disposable AA batteries are also available (On-One stock batteries and a neat super fast power charger), as well as a neat helmet mount. There's an insanely bright rear LED, too. Reliability and mix and match versatility makes them great long-term value, too.