Polar LOOP fitness tracker: review

About a month ago, I received a Polar loop as a gift and I started to use it.
After a month, I can say that I am quite satisfied about it, also if my first thoughts aren't positive.
The design is pretty elegant, the material is something like an hard rubber, the details are pleasant.

Opened the box, first step to do is measure your wrist and cut the bracelet.
WHAT?!? CUT?!?!
Yes, you have to cut the bracelet, in order to adapt it to your wrist.
Mmmm, this make me very bewildered. Cut a new object, pfff, maybe I don't like it and I want to sell it or give to another one..and I cannot!!
Apart from this initial idea, I take the stripe and measure my wrist, then, as explained in the instructions, I cut the rubber. I repeated this a couple of time, in order to get exactly my measure.
Infact, Polar needs to be in contact with your skin in order to get accurate data. All things considered, cut the exact measure of the bracelet isn't a bad idea as seemed.

And then I started to collect data.
I wear it on non-dominant hand, like suggested, and I can see that it's very comfortable.
I spend a lot of time clicking keyboard of a pc and I never found it annoying.
The thickness is about 7-8 mm and sometimes isn't comfortable with tight clothes. But it's not a big problem.

About the screen: there's a led screen that shows different informations.
Since it's a led, it is not visible under sun light. So, in a sunny day I cannot see any information.
The informations displayed are: time, step, calories, and an active percentage.
Active percentage shows a bar that fill as much as I'm active. Usually, the goal is 10k step per day, but the goal changes every day, and it's chosen by the Polar, with an algorithm that I can't understand.
When you reach the goal there's also a "congratulations message", and a notification on the smartphone if it's connected. Someday I need about 20k step to reach the goal, others day 10k is enough. The wrist shows also three type of activity that you can do in order to get the goal.
Step and calories are calculated by some secret algorithm. I cannot say nothing about the calories; I think they are computed based on activity you do every day (this is the trend I understood).

About the step? Well.. obviously, you cannot have really one step counted for every step done.
Algorithms are heuristic, and they aren't very precise; they can get only an approximation of the total step. So, I cannot say nothing about precision of these, but I think there is a variance of 10%.. Not so much.

Polar connects to the smartphone through a specific app - Polar Flow - and uses Bluetooth low energy as protocol. There is the cool possibility to enable airplane mode, in order to get longer battery life.
Airplane mode can be activated/deactivated by long pression of the only touch button present. This button is "touch". It has a capacitive sensor that can notice my finger very well.

Synchronization with the smartphone happens when the Polar is not in airplane mode and the smartphone has Bluetooth enabled. Data are transferred "manually". I receive a silent notification that shows me a spinner bar and asks me to click the button on the Polar to have the transfer started.

Battery lasts 5-6 days with airplane mode mostly activated. I haven't done tests with the airplane mode always disabled. Recharge is made using a specific cable attached magnetically on the rear of the Polar. It needs about 90 minutes to get a full charge and there is a percentage shown on the screen during all recharging. Polar warns that its battery is low at a percentage around 25% and I can get an entire day without recharge from that moment.

Grade: 8/10

Review of the app and the data coming soon...