HQRP Battery for Sportdog SAC54-13735 FieldTrainer 425, 425S, SD-425, SD-425S, SR-225, SR-225S Field-Trainer Remote Controlled Dog Training Collar Receiver + HQRP Coaster HQRP&reg; Replacement Collar Battery plus HQRP&reg; Coaster; Battery Voltage: 3.7V; Capacity: 160 mAh; Li-Pol; 100% compatible with Original Battery; 200 Days warranty!