Bought it from Amazon for $35.00 and put some supplied reflective tape on engine pulley, the Tach showed 3558 rpm for the 11hp Tec full throttle. Seems to be exact and I love to buy small toys like that, beats the hassle to bring it to small engine shop + the cost. Last year I also bought a Lazer temperature digital meter, it's very handy at this time of the year to find outside air leaks in the outside walls near doors and windows. I tend to buy these on the premise I save in the end. Can be used anywhere you can charge beer money at friends.