A big puff kit has three parts: a rechargeable battery, a pod with a built-in mesh coil, and a refill container that tops up the pod. When you inhale, the device senses the draw and heats the coil, which turns the e-liquid into vapour. The refill container feeds the pod as you go, so a 2ml pod can deliver far more puffs than its size suggests.
Multi-pod kits work the same way with extra pods inside. Twist designs let you switch flavours by turning the mouthpiece, while three-pod systems hold different flavours side by side. When the e-liquid runs out, you fit a new pod and refill container, then keep using the same device and battery.