The Digipower PGR-NKD31 Multi-Power Battery Grip is compatible with the Nikon D-SLR D3100 and D5100 camera models. It is designed to double your shooting time by housing an additional Digipower BP-NKL14 or Nikon EN-EL14 battery. The PGR-NKD31 battery grip provides stability when capturing scenes in the vertical format.