Bohning Wind Check Powder
Squeeze the bottle lightly which will release a small amount of powder into the air. Note the direction the powder is heading to ascertain wind direction.
It is recommended to test for wind direction any time the lay of the land changes, if you move from flat ground to low hills, if the pattern of brush changes or if the weather is fluctuating. The general idea is to keep the wind in your face, blowing your scent behind you and towards your tracks and know which direction the wind is blowing.
Small enough to fit into pocket.