A drug delivery device may include a drug reservoir configured to contain and controllably deliver a fluidic drug. A tube may be configured to deliver the fluid from the drug reservoir through a lumen in the tube to another location. A valve wholly within the lumen of the tube may regulates the flow of the fluid through the tube without substantially diverting the direction in which the fluid flows through the tube. The valve may contain only a single member which moves during operation of the valve. The valve may be configured to regulate the flow of fluid in a bandpass manner by allowing fluid to flow through the valve only when the pressure of the fluid is above a minimum and below a maximum. The valve may be held in place within the tube solely by frictional force between the valve and a wall of the tube.