CTA Digital DB-BK1 NP-BK1 Rechargeable Lithium-Ion Battery (1075mAh, 3.6V) Replacement for Sony NP-BK1 Battery Replaces The Sony Np-Bk1 Battery 770mAh, 3.7V Retains full capacity, free from memory effect Lithium-ion for maximum battery life power 3 Year Warranty