The Sony BP-L40A is a professional-grade rechargeable lithium-ion battery pack with a nominal voltage of 14.4V DC and a capacity of 43.2 Wh (watt-hours). It is specifically engineered for use with compatible Sony equipment whose operating instructions recommend its use, such as various DXC and DSR series camcorders. A key advantage of the lithium-ion technology used in the BP-L40A is the absence of a "memory effect," meaning the battery can be recharged at any time without needing to be fully discharged first, which helps maintain its overall lifespan.