Vertax D15 is a battery grip for Nikon D7100/D7200 cameras which can be installed with one battery of EN-EL15 or six batteries of AA/LR6. A D15 grip equals to an extra battery that can double the power. It is indispensable for shooting outside. The battery grip is equipped with multiple buttons which make the shooting easier. The quality is comparable with the one in the original factory with the super workmanship and performance.