A variable flexibility adhesive system may adhere a surface of a medical infusion device to the skin of a user. The system may be configured to hold a location on the surface stationary with respect to a site on the user's skin. The system may include an adhesive substrate for adhering to the user and an interface where the substrate is held to the surface of the device. The interface may totally and/or partially surround the stationary location. A skirt of the substrate may totally and/or partially surround the interface. Parts of the skirt may be stiffened. Optional features may include tabs for activation of the adhesive and/or a location for peeling the infuser away from the skin. Additionally or alternatively, the interface may have variable flexibility. Additionally or alternatively, the stiffener may include a plastic layer.