Electric double layer capacitors and supercapacitors are a class of electrolytic (polarized) capacitors that offer exceptionally high capacitance values in relation to their physical size and low voltage ratings; individual devices have ratings of a few volts at most, though products incorporating numerous series-connected devices to achieve higher voltage ratings are available. Exhibiting losses that are generally high by standards of other electrolytic capacitors yet low in comparison to electrochemical cells, they are often used as alternatives to the latter in applications requiring high cycle counts or power density.