This is either a homemade rechargeable battery or capacitor made from two stainless steel bowls. I am using a saltwater electrolyte consisting of bottled water and sea salt.. This is probably is a high capacity electrolytic capacitor but I am not sure. The type of stainless steel is unknown. The cat food bowls were purchased from my local dollar store. The metal makeup is probably iron, nickle, and chromium but the ratio is undetermined. A magnet is mildly attracted to it. The voltage is about .5v when charged with a 1.5v to 3v source. It is the same as my all aluminum battery shown in my last video that was made from one Al soda can.