I purchased a Digital Photo Sensor Tach SKU 66632. The photo sensor would read a stationary object as having a speed of over 760 rpm with no way to calibrate it. I returned to the store where it was purchased for an exchange. Before I completed the exchange I wanted to try the new unit in the store to save myself another return trip. All three units on the shelf were also defective as witnesses by the cashier and manager. I was then informed that there would be a 20% restocking fee if I wanted to return the defective item or I could exchange it for one of the other proven defective items. Seriously are these people insane? Sell me trash and then penalize me. Are they going to restock the defective item and sell it to another unsuspecting customer? If not why the restocking fee. I was willing to exchange it for a functional unit but they could not provide one. Then I am penalized for their failure and poor products. In my opinion they probably make more profit from restocking fees than actual sales. They have lost my business forever and I will relay my experience everyone I possibly can.