A perfect match for our sew-able coin cell holder. This non-rechargeable coin cell is CR2032 sized: 20mm diameter, 3.2mm thick. It has a nominal voltage output of 3V (although it starts a little high at 3.2V and slowly drifts down to 2.5V as it is used. The capacity is 220mAh assuming a draw of constant 3nA. For other drain rates the capacity may be reduced, check the datasheet!