Works like a charm with the 600 rpm TopCon. Very cool product and is pretty much idiot proof. What's very nice is that once the beam hits anywhere on the receiver, it registers grade. You don't have to precisely line up the center of the receiver to take a measurement, much faster this way. Once you take a benchmark reading, you press the Set button. When you take your next reading the display indicates "cut" or "fill" in the unit of measure you have selected. Granted doesn't really do anything you couldn't do the old fashioned way, but does it faster and reduces the margin of error. Unit is a bit heavy at 8 lbs. Seems pretty durable. I'll report back once it's dropped a couple of times. As of now it gets a two thumbs up, buy it review. BTW, also has a tape measure mode that measures height. You extend the masts until the top of the receiver touches or lines up with what you want to measure. Press the button and it takes a shot from the base to the top of the receiver and registers the measurement on the screen.