The HS34 clips on the ear and the cord runs behind the ear, so they won't come off during exercise. The water resistant (IPX2 equivalent)* design guards against sweat entry making them ideal for sports use.
* Specifications are equivalent to IPX2 of IEC 60529.
The clip hanger keeps the HS34 firmly held to the ear, and the position of the inner part can be adjusted for a comfortable fit. Multiple colour variations are available so you can coordinate with your sportswear and shoes.