Activa Swiss Watch stainless steel back

Activa Swiss Watch stainless steel back Swiss parts MOVT Quartz Water resistance 30M Swiss register number 495494 There is no battery, so I don't know if it works. I couldn't figure out what size battery it takes as there was not a battery when I bought it in it. Otherwise, I would have replaced them. if you do know, please comment. thank you for looking.