2x Pack - Sony MDR-970RK Battery - Replacement for Sony BP-HP550-11 Headphone Battery (700mAh, 2.4V, NI-MH) Replacement Sony MDR-970RK Battery Replacement for Sony BP-HP550-11 Headphone Batteries Quantity: 2, Lifetime Warranty Capacity: 700mAh, Upstart Battery Brand On Sale for a Limited Time!