HQRP Gumstick Battery for SONY WM-EX2000, MZ-R900, MZ-E900, MZ-E909, MZ-EP11, MZ-M10, MZ-M100, MZ-R900PC, MZ-R900DPC Portable CD/MD / MP3 / Tape Player plus Coaster HQRP&reg; Rechargeable Battery plus HQRP&reg; Coaster; Battery Voltage: 1.2V; Capacity: 1450 mAh; Ni-Mh; Rechargeable up to 500 times; 200 Days warranty! Please note that this battery is not compatible with Sony LIP-4WM Battery;