For use in classic car restoration. Ideal for cleaning drip troughs, weatherseal channels, windshield gutters and other small areas that cannot be reached with a large brush or detachable screen. I expected them to fall apart within 15 minutes but they didn't. I've probably got a full hour or more for the first one, which is still going strong. Use with a cordless drill at high speed. Note that they have a hex shaft so they won't fit in a 1/4" collet like a grinder.