Cartridge system for mixing and applying a mix of a medical cement. Cartridges are arranged parallel to each other and an outlet opening. The cartridges each comprise at least one opening that connect(s) the cartridges to the outlet opening, and the cartridges are bordered laterally through cartridge walls. Each cartridge comprises a feed plunger for expelling starting components of the mix from the cartridges through the openings. The feed plungers are fixedly connected to each other through at least one fin. The cartridge walls of the cartridges are connected through the fin(s). The walls comprise slits that are arranged parallel to the cartridge axis, whereby the width of the slits is well-suited for taking up the fin or fins, and the at least one fin moves through regions of the slits when the feed plungers perform a motion in the cartridges.