A device that allows for either fat graft preparation or cell fraction harvest is disclosed. The device includes a first centrifuge tube configured to receive and process a biological substance, the first centrifuge tube comprising an upper cylindrical portion and a lower conical portion, a sterile tissue inlet fitting, at least one sterile processing fluid inlet fitting, a sterile suction fitting, and at least one sterile extraction port connected to a first extraction tube. The first centrifuge tube further includes an internal space including a screen being positioned therein, the screen being configured to divide the internal space in half, and a filter positioned therein, the filter being positioned below the screen in the lower conical portion of the first centrifuge tube. The device may further include a second centrifuge tube configured to receive and further process the biological substance from the first centrifuge tube. The second centrifuge tube has at least one sterile fitting, wherein the second centrifuge tube is releasably connected via the at least one sterile fitting to one of the at least one sterile extraction ports of the first centrifuge tube.