what size are lr44 batteries?
LR44 1.5V Battery is a 1.5 volt alkaline button cell battery designed for general use. The LR44 1.5V Battery is widely used in watches, calculators and medical devices. A button cell battery is a small, round battery that is 11.6mm(0.457 inch) in diameter and 5.4mm(0.21 inch) thick.