It is an integrated chest strap and heart rate monitor designed to measure the user's heart rate.
The H7 sends data wirelessly via either a Bluetooth data transmission to a compatible smartphone with supported heart rate service applications or to compatible Polar devices using a coded transmission.

Compatible with the below Smart Devices :
iPad (3rd & 4th generation)
iPad mini
iPhone 4S
iPhone 5
iPhone 5C
iPhone 5S
iPhone 6
iPhone 6 Plus
iPod touch (5th generation)
HTC One M8 with Android 4.3 or later
HTC One Mini with Android 4.3 or later
HTC One with Android 4.3 or later
LG G2 with Android 4.3 or later
LG Nexus 4 with Android 4.3 or later
LG Nexus 5 with Android 4.3 or later
Motorola Moto G with Android 4.3 or later
Motorola Moto X with Android 4.3 or later
Samsung Galaxy S3 with Android 4.3 or later
Samsung Galaxy S4 with Android 4.3 or later
Samsung Galaxy S5 with Android 4.3 or later
Samsung Galaxy Note II with Android 4.3 or later
Samsung Galaxy Note III with Android 4.3 or later
Sony Xperia Z1 with Android 4.3 or later

Compatible with the Below Polar Products : FT1, FT2, FT4, FT7, FT40, FT60, FT80, RS100, RS300X, RS400, RCX5, CS100, CS200, CS300, V800, Loop

Dimensions : Chest Size: 27 to 60" / 68.6 to 152.4 cm
Battery : CR 2025
Battery Life : 200 hours
Sealing : FPM O-ring

Material
Connector: Polyamide
Strap: 38% Polyamide, 29% Polyurethane, 20% Elastane, 13% Polyester

Operating Temperature : 14 to 122oF / -10 to 50oC