An infusion device system comprising: a disposable housing assembly comprising: an infusion device mating assembly attached to the disposable housing assembly comprising a piercing needle ; and a reservoir , wherein the piercing needle fluidly connected to the reservoir; and an infusion device comprising: a top portion comprising an introduction needle ; and a bottom portion comprising a septum and a cannula , the top portion removably attached to the bottom portion, wherein the introduction needle is configured to insert the cannula, and wherein the top portion is removable from the bottom portion after insertion, wherein the infusion device mating assembly is configured to attach to the bottom portion of the infusion device, wherein the piercing needle is configured to pierce the septum, and wherein when the infusion device mating assembly is attached to the bottom portion of the infusion device, the cannula is fluidly connected to the reservoir; characterized by the infusion device further comprising a length of tubing comprising a first end and a second end wherein the first end of the tubing is configured to attach to the bottom portion of the infusion device and the second end of the tubing is configured to attach to the infusion device mating assembly . a disposable housing assembly comprising: an infusion device mating assembly attached to the disposable housing assembly comprising a piercing needle ; and a reservoir , wherein the piercing needle fluidly connected to the reservoir; and an infusion device comprising: a top portion comprising an introduction needle ; and a bottom portion comprising a septum and a cannula , the top portion removably attached to the bottom portion, wherein the introduction needle is configured to insert the cannula, and wherein the top portion is removable from the bottom portion after insertion, an infusion device mating assembly attached to the disposable housing assembly comprising a piercing needle ; and a reservoir , wherein the piercing needle fluidly connected to the reservoir; and an infusion device comprising: a top portion comprising an introduction needle ; and a bottom portion comprising a septum and a cannula , the top portion removably attached to the bottom portion, wherein the introduction needle is configured to insert the cannula, and wherein the top portion is removable from the bottom portion after insertion, a top portion comprising an introduction needle ; and a bottom portion comprising a septum and a cannula , the top portion removably attached to the bottom portion, wherein the introduction needle is configured to insert the cannula, and wherein the top portion is removable from the bottom portion after insertion, wherein the infusion device mating assembly is configured to attach to the bottom portion of the infusion device, wherein the piercing needle is configured to pierce the septum, and wherein when the infusion device mating assembly is attached to the bottom portion of the infusion device, the cannula is fluidly connected to the reservoir; characterized by the infusion device further comprising a length of tubing comprising a first end and a second end wherein the first end of the tubing is configured to attach to the bottom portion of the infusion device and the second end of the tubing is configured to attach to the infusion device mating assembly . <EOS>