John Van Den Nieuwenhuizen's HiddenRadio has either no user interface...or...is all user interface. That's because, instead of having an obvious "control panel", the entire product itself is a control...okay, that's as clear as mud, let me elaborate...As you lift up the cap on top of the device, the volume of the radio increases proportionally. Likewise, if you push the cap down, the volume decreases until the point at which the device is silent (i.e. switched off). To tune the radio you simply rotate the cap.