usb fans ?

bought 3 fans on ebay they didn't say anything in discription on being usb powered , whats you thoughts return and get wall plus ones or just use these ? I have a ton of phone wall plug ins I can use to use these outta the wall but i'm afraid the wire is to small and after being on it will heat up the cord even if only ran half a day at a time ….whats your thoughts

I cut a hole in a mini greenhouse, taped some 4" ducting in, and stuck a USB fan in.
Moves enough air to keep it under 100f, but thats just keeping convection going.

Maybe use it as a booster fan for a duct, won't do much else at 500mA.
Works great for spot use, and for little seedling trays on a sunny desktop, but the bearings give out using 24/7 duty.

2 of the 5 fans in my tent moving air around are the usb style, and actually my favorite out of the 5 I have. No need to return them unless they suck juice like a slut

unless you have the cord on top of a ballast or something you are fine