Within your fisheries, you"ll find sweet spots in troll speed for all your applications, and with precise measurement, you can fish more effectively, more often. Speed measurements via on board electronics leave a lot to be desired. GPS "speed over ground" measurements do not account for the effects of tide and current flow on lure action. The Luhr Speed troll speed indicator operates on a simple, mechanical measurement of speed that accounts for the exact conditions your lure is running in. Measuring accurately to within 1/10 of a knot, precision control can be provided to all your presentations. Many anglers customize the large readout dial with tags to highlight target speeds for specific lures and/or techniques.