When you’re stalking or still-hunting, even the slightest puff of air can take your scent to the animal you’re after. But it’s very difficult to determine the precise direction of a light breeze.

This simple tool helps you solve the problem, and you can make one in less than a minute. Just place 4 or 5 tablespoons of fine white ash from a campfire into a small porous burlap bag, such as a to bacco pouch (the kind that’s sold for roll-your-own cigarettes). When you want to know what the wind is doing, just remove the bag from your pocket and give it a quick shake. A puff of “smoke” will sift out into the air and show exactly, not approximately, what the air is doing, even when you can’t detect any wind movement at all. To keep your pocket clean, store the pouch in a sandwich bag.