The music GPS watches can play the following MP3 and Advanced Audio Coding (AAC) files:

MP3
Sample rate: 16KHz to 48KHz
Bit rate: 8 kbps to 320 kbps
Mono/stereo channels and joint stereo.
Artist, track title and length are displayed for the following languages: English, Czech, Danish, German, Spanish, French, Italian, Dutch, Norwegian, Polish, Portuguese, Finnish and Swedish. Other languages may display correctly if they only use characters available in a supported language.

AAC
MPEG2 and MPEG4 AAC-LC and HE-AACv2 are supported.
Sample rate: up to 48KHz
Bit rate: up to 320 kbps
Mono/stereo/dual mono are supported.
Artist, track title and length for AAC is not supported.
The watch does not support files with DRM of any type.