The Barb fire coil is one of the best premade sub-ohm coils out there. The coil is comprised of dual twisted ribbon kanthal wire wrapped around a quartz rod and then housed in a ceramic-lined base chamber. The twisted coil creates more surface area to contact any smoking material present in the chamber. This efficiently produces a larger than normal plum of vapor. Or at least, a much larger plum than what is produced by smaller coils on standard vape pens. This is truly one of the best functioning coils available for purchase.