This is the Mini 4WD Speed Checker from Tamiya.
FEATURES: This battery operated instrument is for use with Tamiya's 1:32 scale Racing,Super and Fully Cowled Mini 4WD motorized models. The Speed Checker components include: -Display (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. Detailed instruction manual.