HQRP Portable CD/MD / MP3 Battery for Energizer ER-GUM1 / ERGUM1 Replacement plus Coaster HQRP&reg; Rechargeable Battery plus HQRP&reg; Coaster; Battery Voltage: 1.2V; Capacity: 1450 mAh; Ni-Mh; Rechargeable up to 1000 times; Compatible with Original Battery; 200 Days warranty!