This driveway alert works perfectly every time. I have not yet buried the sensor under the driveway because of the frozen ground. I have it lying parallel to the side of the driveway tucked behind a shrub. Even with the sensitivity turned way down, the sensor has picked up every vehicle. The transmitter unit is constructed very well. I has heavy rubber seal around the door that prevents any water from entering the compartment. Cheaper units I had considered were known to have water leak into them. This unit cost more then I wanted to pay at first, but I am not disappointed. I expect many years of reliable operation.