The FDK VH2100 is a 4/5 AF size rechargeable Nickel Metal Hydride (NiMH) battery. Please note that these cells are flat top industrial cells and are designed for battery packs and industrial applications. The FDK VH2100 is a direct replacement for the VARTA VH2100.
The cells are 1.2V with a capacity of 2100mAh. If you are looking at this battery to go into an electric toothbrush you will need the tagged or off set tagged version of this battery, found in the related products section on this page.