The BG-P1 Battery Grip from Vello is designed for use specifically with the Panasonic Lumix GH3 and GH4. The grip holds one DMW-BLF19 battery while another is in the camera, thereby effectively doubling your shooting time.
The design of a battery grip offers a comfortable and secure way in which to hold your DSLR, especially in the vertical position. The BG-P1 has an alternate shutter release button, AF/AE lock, white balance, ISO, EV, and Function buttons, plus front and rear command dials to facilitate shooting when held vertically. It is designed with anti-slip rubber grip to further improve handling, and a metal mount for attaching a camera strap. Storage spots on the top of the grip help ensure that you won't lose the camera's rubber contact cover, or the grip's contact cover.