New 3.7v 400mah Li-polymer Battery For Polar V800 Sport Watch Accumulator +tools - Digital Batteries - AliExpress
Amazon.co.jp: Polar V800 HR. Colour of product: Black, Water resistance: 3 ATM, Waterproof up to: 30 m. Heart rate data transfer: USB, Distance system of measurement: Imperial, Metric, Clock mode: 12h/24h. Display