Micro TFV4 is designed to offer three types of heating cores for different vaping needs: sub-ohm core (0.3Ω Micro CLP2), standard resistance core (1.8Ω Micro MTL) and rebuildable single Clapton core (Micro RCA). Along with two larger replacement glass tubes and two extension adapters, the original 2.5ml tank can be extended to 3.5ml and 5ml so that you can enjoy Micro TFV4 anywhere and anytime. Top refill design makes filling as easy as it gets. Constructed from superior-quality stainless steel and glass, Micro TFV4 will bring you unexpectedly excellent taste! Innovation keeps changing the vaping experience!