This ADVENT 6520, 6521, 6522 Replacement Battery is 100% compatable with the BP340S1 ADVENT 6520, 6521, 6522 Replacement Battery. Our batteries and accessories are made with high quality parts and are guaranteed to meet or exceed the original equipment manufacturers specifications at a reduced price. All batteries are tested for 100% quality control assurance. This ADVENT 6520, 6521, 6522 Replacement Battery includes a warranty to guarantee that it has no manufacturing defects.