The other night, I forgot a battery for my lights, and thus ended up borrowing a light from Tobie at North Central Cyclery. To my great delight, he had a Gemini Duo charged up, ready for use.
I ran it for a ~100 minute gravel ride, in pitch-black conditions, in the country.
Very simple: battery pack, cord, light head.
The battery pack is compact. One of my favorite features is that the strap that you use to secure it is velcro and elastic. That means you can really snug down the elastic and get a good, tight, wobble free fit. My lights have inelastic straps, and the batteries move around from time to time. The battery pack secured nicely on the side of my toptube, and didn’t move.
The cord is the cord. An extension comes with it, but the stock length was perfect for handlebar mounting.
The light head has an integrated power button. Hold for on/off. Press to switch between the 3 power levels (low/med/high) (See BPaul’s comment, below–there are actually 10 settings, and you can select which 3 you want to toggle between). Intuitive and simple. I tried all 3 levels. Low was more than adequate to ride with confidence on gravel at a good clip. Medium was akin to the output from my MagicShine lights. High was something like car headlights. It was really, really bright. The shape of the light output was a nice oval that gave good visibility across the road, a little bit of ditch visibility, and again, a lot of confidence. I ran them on high for nearly all of the ride, and started with a green light (battery full)…and ended with a green light. I understand it turns orange when you get to a lower state of charge, and then turns red and drops light output. I cannot comment on run times, except to say that I ran it, mostly on high, for a little under 2 hours and the green light stayed lit.
The parts have a nice feel and appearance to them, and the light head is nice and low-profile. With 33 degree temps, I didn’t have any problems with heat, obviously.
Gemini is definitely worth checking out. If I was getting lights tomorrow, they’d be at the top of my list.
Of note…while this is probably not recommended…the cables, batteries and lights appear to be interchangeable with Magic Shine components. (After Magic Shine was burning down people’s houses and their primary dealer in the US closed, I am not endorsing Magic Shine in any way. But if you have Magic Shine lights, this may be a good way to incrementally upgrade, while still using some of your equipment).