Gadget review: Fitbit Charge 2 and Flex 2

Fitbit's new Charge 2 range isn't as bulky as the Blaze or Surge, but comes with interchangeable strap options and a new relaxation mode.

They're a bit too expensive as a stocking stuffer, but Fitbit's new range could be Christmas essentials for the fitness fanatics in your life.

What are they? The all-new fitness trackers from Fitbit that land just in time for Christmas. The Charge 2 updates Fitbit's original model with new colours and interchangeable straps, while the Flex 2 is so fashion conscious it doesn't even look like a fitness tracker at all. In fact, if you don't want to advertise your love of fitness on your arm, it's perfect.

What do they do? A lot of new stuff. For starters, if you're having a spaz out at work, the Charge 2 now comes with short guided breathing sessions to help you work through it, as well as more watch face options. And while the Flex 2 won't actually tell you the time, it's a more discrete option that Fitbit lets you use as "a band, bangle or pendant". Perfect for hiding under a shirt if you don't like watches.

The Charge 2 comes with interchangeable straps, new watch faces and a new relaxation mode.

How do they work? Firstly, as fitness trackers. Both options will monitor your steps and track your sleep, with your stats sent seamlessly to your smartphone app. The Flex 2 won't measure your heart rate, but it comes with one very cool bonus - it's the first ever waterproof Fitbit. If you're a swimmer, that's a big plus. And thanks to its small removable interior, it's easy to change between those accessories - depending on which ones you own.

The Flex 2 can be worn as a bangle, pendant or necklace.

Any downsides? After a month of use, my Charge 2 is blemish-free and works like a dream. The tougher strap and interchangeable strap options mean it has almost replaced my Blaze as my favoured Fitbit. And while the Flex 2 isn't something I'd wear, I'm told the small size and style options are definitely a positive. The only quibble is how much all those accessories cost: a leather strap for the Charge 2 is another $129.95, while a gold bangle for the Flex 2 is $179.95.

Okay, so how much are they? The Charge 2 is $269.95, while the Flex 2 retails for $169.95. A little more than a stocking stuffer, but a perfect gift for any fitness fanatics in your life.