Anything you can use that will forecast barometric pressure swings will work.. i like the one on my phone because it breaks it down in 3hr segment(6 a.m., 9a.m., 12p.m.,3p.m., etc). It shows it in "graph" form and shows up to two days ahead. If i see tommorrow at 1pm that the barometer is goin to start dropping hard -i hunt!!! It is unbelievable how reliable the barometer is forecasting deer movement. Anyone who doesnt use this tool is missing out in abig way imo.