Features： 1、This sensor collector can collect the cycling speed to help you ride in safe speed and protect your body 2、Sensitive chip supports bluetooth, suitable for working with bike computer, smartphone, etc 3、Ultra light and mini size, with strong sticker on the back, comes with a strap for firmer installation on bike hub 4、Waterproof grade is up to IP7, shows no fear to harsh weathers 5、With built-in battery, standby and working endurance are up to 300 days Specification： Features: This sensor collector can collect the cycling speed to help you ride in safe speed and protect your body. Sensitive chip supports bluetooth, suitable for working with bike computer, smartphone, etc. Ultra light and mini size, with strong sticker on the back, comes with a strap for firmer installation on bike hub. Waterproof grade is up to IP7, shows no fear to harsh weathers. With built-in battery, standby and working endurance are up to 300 days. Specification: Material: ABS Color: Black Waterproof: IP7 Battery: 1 x CR2032 battery (included) Endurance: Approx. Standby-450 days; Working-300 hours Connection: Bluetooth 4.0, ANT+ Detection Range: 0-70 km/h Size: Approx. 15 x 28 x 38mm / 0.59 x 1.1 x 1.5in Weight: Approx. 24g Package List: 1 x Wireless Bike Speed Sensor 1 x Battery 2 x Rubber Bands Package List：