Abstract: A defrost or thaw measuring device has a dumbbell or hourglass-shaped rotatable compartment with a cavity, the cavity being partly filled with at least two phase change materials having different melting points. The measuring device may determine the time period of thawing at two or more temperature intervals in the refrigeration space.
Abstract: An interactive physical display is provided. The display provides specific components of a system, such as a braking system, devoid of certain conventional features such that system operations are visible. An actuator for communication with a user is provided, the actuator allowing a user to activate features of the system.