Lanparte DMW-BLF19 Power Coupler DC Dummy Battery Pack for Panasonic DMC-GH3 DMC-GH4 with standard DC 5521 jack Note:The input voltage is between 7.4V-8.4V Compatible with Lumix DMC-GH3, GH4 only Some times you don't want to change battery when shooting, using this dummy battery pack you can use the outsource power to use the camera for all days.