Awkwardly fumbling with nipples when you're trying to center them and drive them into your rim is a pain, but with the Park Tool Nipple Driver the job is easy and quick. All you need to do is center the driver on the nipple, and it easily threads conventional nipples for easy wheel building. The Nipple Driver is built with a dual density grip for comfort during use, and is lined with precision bronze bearings to make sure it runs for a lifetime.