Which one? All mechanical, preferably button on bottom. Native 510 fitting. Battery life similar to or better than an ego. I really liked the spark plug but it doesn't have a 510. Are there any smaller tube mods than the SP? Thanks.
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It won't be mechanical if you put wires and chips in there. The negative is always the body of the mechanical mod. As for the GGTS, there is a center pin which gets in contact with the positive side of the battery and touches center of the atomizer.