The Polar Wear Link+® transmitter Nike+ monitors heart rate & transfers this data into the Nike+ system. With its hook mechanism, the transmitter is quick to put on & take off. It features machine-washable soft textile strap & water-resistant connector. The textile chest strap easily adapts to the users body shape leaving full freedom of movement. When used with compatible Nike+ devices, the Polar Wear Link+ transmitter provides heart rate information to nikeplus.com web service. The transmitter can be used with the iPod nano & iPod nano Multi-Touch 5th generation or later, Nike+ Sport B&, Nike+ Sportwatch GPS & Polar training computers using 5 k Hz data transfer.