Great gadgets!

Shape, July, 2004

Stay on top of your vital signs with these handy devices.

EON Hydra-Alert Watches (from $150; acumeninc.com) gauge your exertion, along with the temperature and humidity, enabling you to accurately assess your hydration needs as you exercise.

Caltrac ($70; 800-522-5872, caltrac.net) looks like a clip-on pager, but actually informs you of the number of calories you're torching wherever you go. Enter the amount of calories you've eaten throughout the day to see if you've burned more than you've consumed.

Dual Sports Digital Music Player/Heart Rate Monitor ($280; digisette.com) is a wireless heart-rate monitor, FM radio and shock- and skip-proof MP3 digital-audio player combo that's easy to use.--L.L.