Is it necessary to bring a watch when running?

Of course, you need to record your heart rate and heart rate. How light the watch is, bring a mobile phone.

armband

I'm still worried that my mobile phone will fall out when I run. I will buy an entry-level belt of about 400.

satellite positioning

A sports watch will do. I use 75 W20 with triple satellite positioning, and the power is also very durable. It is made in China.

Garmin

Plane replacement.