Rail Cant Measuring Device is a High Quality Railway Measuring Tool / Cheapest Rail Bottom Slope Measuring Instrument .The main part of the wheel tread is the 1:40 slope.To make the top of rail fore evenly under the load of a conical tread wheel.Rail should be tumbling-in not vertical.the inner inclination of therail is called rail bottom slope.The product is easy to use,both in the daytime and at night.It is an ideal measuring tool for public works and engineering departments.