I'm echoing what TSL said, and will add that the people I dealt with at Geoman were unusually customer orientated - I have the MS 900 lumen light, and an MS taillight (comes with a Y-cord, so you only need one battery. Couldn't be more pleased. I only commute 5 miles each way, but it is through a construction zone, so lots of rough riding - so far no problems. I'm also considering buying another from Geoman. I imagine I could get my wife to ride at night with me, these lights are so adequate. If I can't, I might just pop a second system on my ride. The new Geoman battery pack has a truly awesome fixing strap - you can stick it anywhere and as long as you pull the velcro tight, it'll stay.