We present a haptic wristwatch prototype that makes it possible to acquire information from a companion mobile device through simple eyes-free gestures. The wristwatch we have built uses a custom-made piezoelectric actuator combined with sensors to create a natural, inconspicuous, gesture-based interface. Feedback is returned to the user in the form of haptic stimuli that are delivered to the wrist. We evaluated the capabilities and limitations of our prototype through two user experiments. One experiment verified that the apparatus could be used as a tactile notification mechanism. The other experiment assessed the feasibility of using a cover-and-hold gesture on the wristwatch to obtain numerical data tactually. Results from the numerosity experiment and feedback from participants prompted us to redesign the cover-and-hold gesture to provide users with additional control over the interaction. We qualitatively evaluated the redesigned interaction by handing the prototype to users so that they could use it in a realistic work environment. Taken together, results from the experiments and the validation process indicate that a wrist accessory can be effectively used to perform discreet, closed-loop, eyes-free interactions with a mobile device.