Features: Being a sensor type heart rate monitor， it will detect and send your real-time heart rate to the smart phone accurately.Compatible with iPhone 4S and later， and with selected Android devices including Samsung Galaxy S3 and S4 using Android 4.3 or later.Supported apps: Wahoo Fitness， Fitcare， 60Beat， RunKeeper， Strava，  MapMyRun， Endomondo， Sprots Tracker etc.With the chest strap based on high quality material， it can be attached to your skin closely.This Bluetooth 4.0 technology supported device is very fashion and creative.The most popular heart rate monitor in the world easy to use yet is very durable.Ultra low power consumption， with a replaceable CR2032 battery.Specifications:Material: ABS + Plastic + Silica gelColor: BlackBattery: CR2032Technology: Bluetooth 4.0LE(Low energy)Transmission: Wireless BluetoothTransmitter size: Approx.6.5 * 3.8 * 0.8cm / 2.5 * 1.5 * 0.4inTransmitter weight: Approx.18g / 0.6ozBelt size: Approx. 100 * 3cm / 39.3 * 1.2in(before-stretching); 160 * 3cm / 63 *1.2in(after-stretching)Belt weight: Approx.35g / 1.3ozPackage size: Approx.17.5 * 7.5 * 2.2cm / 6.9 * 3 * 0.9inPackage weight: Approx.97g / 3.4ozNote:Transmitter: Attach it to the strap in the right directions.Battery: Open and close it with a coin.Package List:1 * Transmitter Device1 * Adjustable Elastic Strap1 * User Manual(English)