The Smok RPM C Empty Pod Cartridge is designed for Smok RPM C Pod Kit and compatible with Smok RPM 2 Coil. 3 Pieces Per Pack. With an unprecedented 4ml E-Liquid capacity it features a slide-to-open top filling system and can refill both freebase and nic salt E-Liquid for MTL & DL vaping. Simply push the top filling cover to expose the filling hole without pulling out the pod while keeping the filling process hygienic.