HeroFiber Pro series Multi-Power Battery Grip for Nikon D3100 SLR Digital Camera w Ultra Gentle Cleaning Cloth Double the Battery Capacity Effectively Doubling Your Shooting Time Significantly Improves Stability Especially in Vertical Position Battery Compartment Holds Up To 2 EN-EL14 Lithium ion Batteries Great Quality, Ergonomics, Functionality, and Construction Contains Cover Storage Area to Store the Camera's Battery Chamber Door When Grip is Mounted