As fitness gadgets and smartwatches merge, it is easy to overlook the advantages of straightforward, focused device. This second generation Vivofit activity and sleep tracker adds audible alerts, improved smartphone syncing, and a timer for more accurately tracking your calorie burn during exercise. It’s waterproof to 50m and has a battery that lasts a year so you rarely need to take it off. An improved clasp ensures it won’t dislodge easily. A range of covers designed by Jonathan Adler ($45 for three-pack) gives fashionable choices while the ability to pair it with a heart-rate monitor chest strap adds functionality.