Features:Being a bike speed and cadence sensor， it will detect and send your real-time RPM， speed， distance and other information to you accurately.Based on high quality material， the sensors and magnets can be attached to your skin closely.This Bluetooth 4.0 technology supported device is very fashion and creative.The most popular bicycle sensor in the world easy to use yet is very durable.Ultra low power consumption， the replaceable battery's life will last up to 1 year.Specifications:Color: BlackBattery: CR2032Material: Plastic+silica gelTechnology: Bluetooth 4.0(low power dissipation)Transmission: Wireless BluetoothPackage size: 12 * 4.2 * 11cm / 4.8 * 1.6 * 4.3inPackage weight: 87g / 3.06ozPackage List:1 * Speed Transmitter Wired with RPM Sensor1 * RPM Sensor Mat1 * RPM Sensor Magnet1 * Speed Sensor Mat1 * Speed Sensor Magnet1 * Speed Sensor Fastening Accessory8 * Fastening Lines1 * User Manual(English)Note:Supported devices: iPhone 4S， iPhone 5， iPhone 5S， iPhone5C， iPod Touch 5， the NEW iPad， iPad 4， iPad mini， iPad air.Supported apps: Wahoo Fitness， Strava， MapMyRide， etc.Battery: Open and close it with a coin.