Tachometer

Measuring range: 20-50000 RPM
Accuracy: 2×10-4×N±1digit
Adoption time: 1s(automated)
Weight:300g (include battery)
Measuring distance:  1.97 to 15.75 inch  (i.e., 50-400mm)
Display: 5-digital LCD
Battery: 4×1.5V DC alkalinity battery
Dimension: 3.0X1.50x7.0 inch  ( i.e., 78mm(L)×38mm(W)×180mm(H) )