The ESP1400AAH is a 4/5 AA 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 cells are 1.2V with a capacity of 1400mAh. If you are looking at this battery to go into an electric shaver or toothbrush you will need the tagged version of this cell, found in the related products section on this page. You may also be looking for the CPS533 if you need a shaver battery pack.