Compatible with heart rate sensors: Works with MZ-3. Adjustable sizing: Belt circumference 66cm (adjustable), width 3cm. Easy to use and clean: Utilizes snap attachment method. Sensor transmitter must be removed and soft strap hand-washed as needed. Comfortable and functional: Made of nylon material, attaches closely to skin. Soft fabrics and adaptive electrodes for sensitive detection of heart's electrical signals. Note: Only strap included; heart rate sensor transmitter not included. Color as shown in the picture. For the heart rate belt, center distance of buttons is 45mm. Please confirm the button distance on the back of heart rate module before purchasing. Package Contents: 1 x Strap. Only the above package content included; other products not included. Note: Light reflection and different displays may cause color variation. Measurement allowed error is +/- 1-3cm.