KOOLSTOP Presta Valve Adapter
If you came looking for these then you know what they are. If you are relatively new to bicycling or happen to purchase a vintage bicycle and realized that the air hoses around town won't fit the stem on your wheel, then you need one of these. These are PRESTA valve adapters and screw on to a conventional (Schrader) tube stem and allow you to inflate your tire. Presta tubes are typically a sign of a quality bicycle that uses high pressure tubes and tires for smoother, faster rides. Don't worry...its a good thing!