This black Vertical Battery Grip from Sony allows for long-term, comfortable shooting in the vertical orientation with your Alpha a7 or a7R digital camera. It accepts 1-2 NP-FW50 batteries, which are available separately, to extend and possibly even double your shooting time. The grip uses a battery with lower power first, then automatically switches to the one with greater power when the first runs out. Remaining battery power is displayed as a percentage on your camera's LCD monitor. Additionally, batteries can be replaced without turning off the camera.