Exell Battery Replaces Sony Headset BP-HP550 1-756-316-21 1-756-316-22 Sony MDR-DS3000 MDR-IF240RK MDR-IF3000 MDR-IF540RK MDR-RF820 MDR-RF885RK MDR-RF920RK MDR-RF960R MDR-RF960RK BF-TDSY MDR-RF925RK