I use a lot of these for cleaning automotive electrical connections and lamp sockets. When used hard, they don't last all that long, but that is to be expected, as the wire bristles are very fine and will slowly break. As such, when using these (or any similar type product), be sure to wear an apron and eye protection! A wire in the eye can ruin your whole day! These are a much better deal than the official ones sold by the makers of the rotary tool.