With Its Vapor's Ohm Tester, you can easily test cartomizers and atomizers without having to use a complicated meter. You just simply screw on a cartomizer or atomizer and this tester will show you the ohms. This tester is also great for checking or for bad cartomizers or atomizers. This ohm meter will read a 1 in the first digit to the left if there is no current flow through the device. Accurate to +-0.4%. Will read from 0.01 to 9.99 ohms. Runs on 2 AA Batteries.