. >> host: joe atkin, what if you're in a place where there's no sun sign? >> guest: -- sunshine? >> guest: they also charge off the wall and car chargers. so i guess there's no sun, a pretty dark place because they also charge off cloudy conditions or if it's rainy, so even like our users in europe, london or u.k. or whatever, they can power it up no problem. so it doesn't have to be totally sunny like it is right now. it just, it can charge in cloudy conditions as well. >> host: how long will it hold a power charge? let's say you charge it for three hours in the sunshine and then you travel? >> guest: yeah. so typically rechargeable batteries like this will last 4-6 months just on the shelf. so it's kind of like a battery in your car that you want to be using it. but this will, this will power a laptop for a couple hours, it'll recharge an ipad a couple times, or if you have, like, a smartphone, two to four times it will recharge it off of one charge. so if you're traveling around, you could charge this up from your house like a wall plug and take it with you on a plane or an ev