I don't know if they used a 18500 or a 18650 batterie in the GGTS on vaportrails.tv.
Depending on how you set up the GGTS. If you put atty at the connector inside the collector tank then the center pin will protrude down making it a tight fit to put anything more than an 18650. If you use a re-threader and 910-510 adaptor to make the 510 connector sit flush with the top cap of the GGTS then the pin wont go out as much and should be able to accommodate the kick inside it. Then again there is always the extension tube for the GGTS if real estate is an issue. I use a single extra extension tube to fit my evercool module this way with 2 18350 batts with rooms to spare.
