The Nike+ SportWatch GPS offers you a new running experience. The GPS receiver works in tandem with the shoe-based Nike+ Sensor to deliver highly accurate pace and distance data while in-run. Adds personalization and motivational features to the running experience, including audible sounds, challenges, run reminders and more. Connects directly via your PC or Mac to www.nikeplus.com. Water resistant up to five ATM (50 meters).
Do I need Nike + Shoes?
I don't really understand the whole sensor thing. If I need nike + shoes then i will just pay another $10 for the watch with a sensor