I'm not even 100% sure that's what they're called. I am about to purchase my first Genesis style atty. I do not know much, but I am aware that you need to check the resistance before attempting to fire it. I only currently have an eGo Twist (I'm hoping to upgrade to a better mod eventually... money for what I want is an issue right now lol) and since it obviously does not read the ohms of the atty, i'll need a separate unit for that. I can't seem to find one that's inexpensive. It does not need to do anything fancy, nor have multiple features. I will be using it ONLY to check the resistance of the coil I wrap before throwing it on my twist. Anyone know where I can pick something up?? TYIA for your time!!