Description: Quality material: This bike speed sensors are made of quality plastic material, which is wear resistant, waterproof, and sturdy. It can be used for a long timeMultifunctional: This bicycle sensor can not only as a speed sensor but also as a cadence sensor, note that the two cannot be used at the same time, it is multifunctional and can meet your different riding needsEasy to use: When this cycling computer is speed sensor mode, it needs to be installed on the bicycle hub; when in cadence sensor mode, it needs to be installed on the crank. It Is Easy to useSuitable size: The length of this bike cadence sensors are 3.8 cm, width 3 cm, and height 1 cm. Its compact structure and lightweight make it portableWide application: This cycling accessory is very suitable for road bikes, adults bikes, mountain bikes, etc., making it a practical accessory for cycling enthusiasts Specification: Material: Plastic Size Chart: 3.8cmx3cmx1cm/1.50inchx1.18inchx0.39inch Package Includes: 1 Bike Speed Cadence Sensor,2 Rubber Rings,2 Rubber Pads Note: Please allow slightly errors 1-2cm differences due to manual measurement.