Main fabric composition: spandex  

product manual:
When running, the cuff can hold the phone, suitable for wrist circumference of about 15-25 cm. It can rotate 360 degrees,
Will not slip.
The cuffs have luminous reflectors and have a clear warning reflection in dark places, allowing you to run more safely at night.
Made of silicone material, it has high elasticity, high hardness, and will not break when pulled.
The mesh back cushion has good perspiration and improves sports comfort.
Lightly press the elastic adjustment button to easily tighten.