This DC Coupler lets you connect to a D-Tap power source using your camera s EN-EL15 battery compartment, providing long runtimes and unrestricted movement! DC couplers provide long-lasting power to a camera and are especially useful for video, long studio shoots, or events. The ProMaster DC Coupler with D-Tap connects to a D-Tap power source such as a V-Mount battery, providing extended runtimes far greater than standard camera batteries while allowing for unrestricted movement. This is an excellent option for powering a camera when using a cage or shoulder rig.