The FS-T4 is the classic tank cartridge for eGo series. It can work for all types of eGo batteries. It has seven different colors for choice: Clear, Smoke Black, Red, Blue, Green, Yellow and Pink. It is easy to refill and has scale to view the liquid. FS-T4 uses the special material without blowout danger. The new special material is healthy and innocuous to human bodies and has no influence to the E-liquid flavor or taste. No leaking or burning problem.