Devices and methods useful for non-invasively indicating the position or setting of a mechanical device, such as a sensor or control in an implanted medical device, are disclosed. In one exemplary embodiment, a valve housing adapted to receive fluid flow therethrough is provided. The flow of fluid through the valve housing can be controlled, for example, by a valve assembly that has a plurality of predetermined pressure settings. A radio frequency tag can be disposed in the valve assembly, and the masking element and the radio frequency tag can be configured to move relative to one another. The relative positions of the masking element and the radio frequency tag can alter the response of the radio frequency tag to a wireless signal (which can be emitted from an external reading device, for example) and thereby indicate the pressure setting of the valve assembly. For example, in some embodiments, the masking element can selectively cover at least part of the radio frequency tag according to the pressure setting of the valve assembly, which can change a characteristic of the radio frequency tag's response to the wireless signal.