Have you ever dropped your phone off the chair lift? Every year a lot of skiers and snowboarders drop their phone from the chair lifts.
I am using "Coil Strap" for not drop my iPhone off the chair lifts.
Attach the coil strap to the iPhone,
Then clip to the pockets.
Last year I almost dropped my iPhone off the chair lifts (in blizzard!). The coil strap saved my phone.
You can buy the "Coil Strap" at the home improvement store in Japan.