LED bulbs, run off of Moonray AA solar batteries that last a long time. Not sure if I've ever had to change them since I got them a few years ago. Depending on the amount of sunlight, they usually run anywhere from 4 to 6 hours each night. Occasionally, I've seen them dimly lit early in the morning before sunrise. They're sold at most stores like Walmart, Home Depot, etc. I used metal poles and painted them black to raise the solar lights up about a foot or so, so they shine down on the pond. They don't really light up the water much, but do a great job of highlighting the stone edge.
The two shining at the pond aren't made anymore, but the company now sells a new one that appears to be the upgraded version, but I'm not sure.
http://www.moonrays.com/20-Lumen-Floodlight-P630.aspx
The one problem I see with that model is that you can't adjust the panel separately. Especially in Spring, the sun is still south so I aim the panels that way.
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The two I use for the bog are still sold, they seem a bit dimer and more of a yellow-ish light, but still highlight the small bog nicely at night. Here's their description:
http://www.moonrays.com/Mini-Spotlight-P387.aspx
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