Replacement Cartridges for Microneedling Pen of Rejuva Fresh® HYDRA Perfection MD™Each pack includes the 20, 50 or 100 pieces of the selected cartridge (refer to picture for selection): These high quality cartridges are for use exclusively with the Rejuva Fresh HYDRA Perfection MD 15 Dimensions Facial Machine Professional. They are used on this machines microneedling handle. Cartridges are strictly disposable. Notice: These cartridges will not compatible if your machine was purchased from another brand vendor, and they are not