The Ego Booster was designed for use with genuine Joyetech eGo and eGo-T batteries, and should not be used with non-Joyetech devices.* Using the Ego Booster with Joyetech batteries (such as Happy eGos, Joye eGos or TWs Tornados) provides an exceptional variable voltage vaping experience. Using the Ego Booster with non-Joyetech fat battery devices (fat batts) will not harm the Ego Booster, but it can damage the fat batts circuitry and may render the fat batt unusable Due to the number of similar appearing devices on the market, determining what is and isnt a genuine Joyetech eGo can be confusing. To make matters even more confusing, some vendors sell non-Joyetech eGo devices with misleading names like Ego or EGO, or, even worse, falsely claim their products are Joyetech when theyre not. A list of some fake Joyetechs can be found at the Joyetech website here. Additionally, Joyetech can be queried directly about the authenticity of a device by emailing email@example.com. But what can you do yourself to determine if your eGo is genuine? With a Multimeter: If your freshly charged eGo or eGo-T, without load, meters at 3.2v 3.4v, then it is most likely a genuine eGo and it will work with the Ego Booster. If, however, it meters at 3.7v or higher, it is not a genuine eGo or eGo-T and should not be used with the Ego Booster. Without a Multimeter: The Name: If its not called an eGo or eGo-T, then it is most likely not a Joytech eGo. One exception to this is TWs Tornado line, but their websites clearly state that the Tornado is a Joyetech product and Joyetech, if asked, will confirm this. The Button: This is the best method weve found to determine the difference between genuine Joyetech eGos and non-Joyetech devices. Look at the two pictures below. Fig. A - eGo In Fig. A This is a genuine Joyetech eGo. The button is clear, hard plastic with a slight indentation. If your eGo (or Tornado) has this button, it most likely a genuine Joyetech and can be used with the Ego Booster. Fig. B - Not an eGo In Fig. B This is a non-Joyetech fat batt. The button is opaque. It has no indentation and feels more like soft rubber. Though button size and shape vary slightly on non-Joyetech fat batt devices (some are oval) they are typically opaque, soft rubber. Any fat batt with an opaque, soft rubber button is NOT a genuine Joyetech eGo or eGo-T and should not be used with the Ego Booster. * The Ego Booster also works with mods powered by IMR high drain batteries, but for the purpose of this article, we will be discussing only integrated fat battery (fat batt) devices.