ue to the different transmission ratios of the different gears of the variable speed vehicle, only in the gear that suits you can try to achieve the best effort and durability, and at the same time achieve high speed, so that your physical fitness can be best used and utilized. This requires a cadence meter to grasp the relation between gear, pedaling frequency, pedaling strength and riding speed. Cadence is mainly for you to maintain a pedaling frequency that is most suitable for you. This frequency is the most relaxed and efficient, and can keep you riding for a long time without fatigue. Measuring heart rate allows you to exercise without having to guess mastering the right intensity to help you achieve your goals efficiently and avoiding excessive or insufficient exercise through heart rate detection; It is easy to check the progress and prove your efforts. please pay attentions to 4 points: 1.the distance between monitor and sensor should below 80 cm 2. the distance between sensor and magnetic should below 3 mm 3. In order to enhance anti-interference, we used ID coding technology in the design. When the battery is just installed, the speed sensor needs to work continuously for 1 minute to recognize the new sensor.Please refer to the video and test for one minute, then check if the speed sensor is working properly 4. Beside point 1-3, the wrong installation of the speed sensor will also cause 0 display. By the way, this bicycle computer is a wireless product, and the electromagnetic waves of the environment will affect its normal operation. When using it, we should avoid the electrical equipment at work: household appliances, high-voltage wires, transformers, high-voltage cables, charging stations, elevators and other electrical equipment at work (code table speed display 0 when interfered with) colour: black Material: plastic Package Contents: 1 x Bicycle stopwatch 1 x Cadence 1 x Heart Reat Only the above package content, other products are not included. Note: Light shooting 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.