The waterproof touch key Necklace MP3 Player Features: - Audio format: MP3, WMA, WAV - USB Flash Drive - Induction earphone Jack: It can play automatically when you insert your earphone into to Jack, and turn off when you take your earphone out from the Jack - Built-in Rechargeable Lithium battery - Long time playback up to 12 hours Specifications: - Size: 42x14x7mm - Weight: 18g - Color: Black, Red, Purple, Orange, White, Green - Memory Capacity: 128M/ 256MB/ 512MB/ 1GB/ 2GB/ 4GB - Interface: USB2.0 (Read: 5-6.5MB/s, Write: 3.5-4.5MB/s) - SNR: >90dB - Frequency response: 20Hz~20kHz - Operation System: Windows 98/SE/ME/2K/XP/VISTA, Mac OS9.0, Linux2.4 or above