I tested the 450 on channel markers, other boats, and even a floating log no larger than a fender. It's easier to use than the range finders in most binoculars, which require you to know the height of the target to determine distance. Just point the 450 at a target, press a single button, and the range in yards pops up in the viewfinder. It can be set to read in meters, too, and gives accurate distances from 5 to 800 yards. The more reflective a target is, the farther the unit's range. It's water resistant and survived several sheets of spray that came over the bow.