GeekVape Z Series XM Boost Coils, 0.15 to 0.4 Ohm, 5 Pack

XM mesh refers to the mesh structure of the coil heating element. Standard mesh coils use a flat woven metal sheet shaped into a cylinder around the cotton wick. The XM design modifies the mesh geometry to increase the surface area in contact with the wick and improve how heat is distributed across that surface during firing. More even heat distribution means more e-liquid is vaporised per unit of heat applied, which translates to better flavour extraction and a more consistent draw from the first fire to the point where the coil needs replacing.

The Boost Version takes the XM mesh structure and optimises it specifically for higher wattage operation. Standard coils at 0.15 Ohm can develop uneven heat distribution at very high wattage because the mesh is being asked to perform at or near the limit of its thermal capacity. The Boost design addresses this by adjusting the mesh density and contact configuration to maintain even performance at elevated wattage without the thermal inconsistencies that can develop in standard mesh at the same resistance and power level.

In practical terms, a Boost XM coil at 0.15 Ohm should deliver a consistent draw across its usable life without the degradation in flavour quality that sometimes occurs with standard coils when run at maximum wattage. If you push your Z tank to the upper end of the recommended wattage range for a given coil, the Boost Version is the more appropriate option over the standard XM.

The 0.15 Ohm coil is the lowest resistance in the Z Series XM Boost range and requires the highest wattage to operate. At 0.15 Ohm, the coil fires at a wattage that produces maximum vapour volume and a fully open, warm direct-to-lung draw. This is high-performance DTL territory suited to experienced sub-ohm vapers with a capable mod. Use 0 to 3 mg freebase nicotine or 0 to 3 mg nicotine salt at this resistance. The vapour volume per draw at 0.15 Ohm makes higher concentrations unnecessary and potentially harsh.

The 0.2 Ohm coil is the middle option. Still firmly in sub-ohm territory, the 0.2 Ohm produces substantial vapour and an open DTL draw at a wattage requirement that is lower than the 0.15 Ohm. Vapers who want the Boost XM performance without pushing their mod to maximum output find the 0.2 Ohm a practical balance. Use 0 to 3 mg nicotine. The 0.2 Ohm is also a longer-lasting option than the 0.15 Ohm in most cases, as the lower wattage reduces the thermal stress on the coil material per firing cycle.

The 0.4 Ohm coil is the highest resistance in the Boost range and the most moderate draw of the three. At 0.4 Ohm the tank fires at a wattage suited to a restricted-DTL to open-DTL style, with less vapour per draw than the 0.15 or 0.2 Ohm. Up to 6 mg nicotine is manageable here. Coming from a pod kit to a sub-ohm tank for the first time, the 0.4 Ohm is the most accessible entry point in the set.

Priming is the difference between a coil that lasts and one that tastes burnt on the first pull. Two minutes, do not rush it.