These are factory-direct replacement cores / coils for your SMOK Penn 22 All-In-One device.  Rock Bottom Vapes carries all four variants for your vaping pleasure.  The SMOK Pen 22 ships with the Dual Core 0.3 ohm coil which features a NiCr heating element.  SMOK also offers a 0.25 ohm dual coil version for those looking for a little more vapor production out of their Pen 22.   Finally there are also the Strip and Mesh versions of the coil which provide a richer flavor.