Coils Atomisers or wicks is generally the term used for these in the e cigarette market, in simple this is the replaceable atomiser/coil fitted inside every cartomiser, clearomiser, or vape tank, its the component that heats your e-liquid to create the vapour you inhale.
Available in various ohm’s and sizes these are always specific to the cartomiser or vape tank and brand you are using. Please ensure you select the correct coils for your device.