Power-on self-test: All segments are displayed on the LCD screen, and the buzzer sounds for 2 seconds simultaneously. After the self-test is complete, the age selection interface "AGE?" appears, and the display age value can be set between 13 and 80. After age selection, press the ENTER key to enter the waiting interface. In this interface, INTERVAL, READY, WORK, REST, TARGET, TIME, DISTANCE, CALORIES, WATTS, SPEED, RPM, and HEART RATE are displayed alternately and cyclically with an interval of approximately 1 second, waiting for the next step. While in the waiting interface, press the START button to begin free training mode. In this mode, the total running time, distance, calories, power, speed, rotation speed, and heart rate are recorded. LCD display shows timing, distance, calories consumed, power, speed, and rotational speed values accordingly. When the STOP button is pressed, TOTAL, AVE, and MAX are displayed alternately, with corresponding values indicating their averages. Displays the heart rate reference value based on the set age at power-on and the detected heart rate during exercise. Actual shipment does not include batteries. No heart rate function included. Batteries: 2 x AA or 4 x AA (more batteries provide longer usage). Color: black. Material: plastic. Package Contents: 1 x Rowing Machine Counter, 1 x Induction Line. Only the items listed are included; other products are not included. Note: Lighting and display differences may cause slight color variations between the image and actual item. Measurement error allowance is +/- 1-3 cm.