Comfortable chest strap for heart rate measurement compatible for , , products. The smart of soft fabrics and adaptive electrodes extremely sensitive to Being an indispensable part of heart rate monitor, it will detect and send your real-time heart rate to the smart phone accurately. The most popular heart rate belt in the world easy to use yet is very durable. Utilizes the snap attachment . This light garment is compatible for all heart rate sensors(ANT+, Bluetooth 4.0, 5.3K). With the chest strap based on high quality material, it can be attached to your skin closely. your electrical signals, so the heart rate sensor can your heart rate quicker and more accurately. Suitable for two transmitters with 45mm spacing between buttons and 5mm center to center Material: Silicone + fiber colour: black Package Contents: 2 x Adjustable Elastic Strap Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.