AT&T is offering the Fitbit ZIP Wireless Activity Tracker for $59, but when you use the code FITBIT50 at checkout, the price drops to $30 shipped. That’s $29.50 off the original sale price/Amazon’s current listing and the lowest we can find.
“This mini-sized, wireless device easily clips to your pocket and tracks steps taken, distance traveled, and calories consumed and burned all in a day” The ZIP is also sweat, rain, and splash-proof with a battery life that lasts for up to six months without charging. Over 8,000 Amazon shoppers gave it 4/5 stars. 
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Be warned! The USB dongle that Fitbit provides is NOT compatible with El Capitan. Fitbit has known about this issue since the beta testing and has refused to address it, instead pointing their fingers at Apple. Don’t take my word for it. Read their user forums.