These genuine Innokin replacement coils are for the Innokin iClear 30S tank and come in a five pack. They are made with quality materials to give the very best experience possible. Each of the heads has 8 wicks, which is 4 per coil which gives a better flow of juice even if the device is not in the optimal position. It is always good to have a decent stock of spare coils as if they are not replaced regularly the amount and flavor of the vapor will be diminished. By having a new coil you will find that you get the best experience from your vape liquid and taste it as it was intended. How often you need to do this will depend on how often you use them as well as the types of e-liquid that you use.