Or an Android phone, but only Android users will be able to reply to messages with preprogrammed quick replies. It mirrors every notification you can get on your phone whether you have an The Charge 4 goes beyond health and fitness tracking with a few smart features up its sleeve. Each morning, the Fitbit app gives you a Sleep Score based on everything from sleep duration to sleep stages, heart rate and variations in blood oxygen levels (SPO2) and skin temperature.

With a 6-month-old baby and a toddler waking me up at odd hours of the night I was scared to even see my stats the next morning, let alone get graded on my sleep. I've never gotten much out of tracking my sleep in the past. Just swipe up from an activity that uses GPS, like running or cycling, and toggle it off. You can do this from the exercise shortcuts on the Charge. You'll just have to remember to do this after your workout.

I didn't mind having to recharge after four days, but if you're looking to get the most out of your battery life (and are planning to use it at night) I would recommend turning off the GPS when it's not in use. Fitbit says the Charge 4 can last up to seven days on a charge, but I barely made it to day four before having to plug it in. The only downside about having GPS on the Charge is that it'll gobble up your battery a lot faster than on the Charge 3. Like the Charge 3, it's also hard to see the screen in direct sunlight. The only time the lag really bothered me was while I was running and wanted to quickly glance at my stats without taking my eyes off the road. The touchscreen isn't as responsive and it takes a few seconds to light up when you raise your arm to wake the screen, but I eventually got where I wanted to go. Instead, you control the Charge 4 with a combination of the touchscreen and by pressing the left side of the tracker to navigate settings. , and it also does away with physical buttons. The screen can only display in black and white, but I like that it's nearly half the size of a traditional smartwatch, such as the , the new version doesn't look much different - it's just the tiniest bit bulkier on your wrist. The $150 Charge 4 (£130, AU$230) is a tracker I will happily wear 24/7 thanks to its sleek, understated design. There are plenty of great wearables for athletes, like the Garmin Forerunner 945 and Suunto 3, that have way more fitness chops than the Charge 4, but they're not the most fashionable. Shorter battery life than the Fitbit Charge 3

Charge 4 fitbit