The Rubi is a small concentrate pen that uses refillable pods. It is similar in form to other new releases using this style of power source. The unique quality of the Rubi is that the pods are available empty. They are quite easy to fill, and I currently am running my 3rd refill in a pod. They seem to hold about .4-.5g. The power source charges via USB. Although the power source is relatively small, it will hold up to a full day of use before needing a recharge. Unsure of the internals of the pod, I have read/heard that there is a ceramic element wrapped in cotton. I don't bother trying to clean the pod before refilling, just top off the level as needed. The pod has a removable plug on its side to allow you to fill with a small gauge syringe. Welcome any fellow owners of this device.