Display that indicates operations & results of measurement On/Off Switch Start Button (starts measuring the speed/lap time) Mode Button (selects "speed check" or "time attack" mode) Distance Select Button (selects virtual running distance on "time attack"mode) Speed Measuring Rollers (rotates according to the car's wheel rotation) Car Stopper (prevents car from leaving the rollers) A buzzer will sound indicating measurement has started. The instrument has an automatic shut-off if left untouched for about three minutes.
One speed checker Detailed instruction manual