A supersonic cooling system operates by pumping fluid. A desired output frequency is received. The present disclosure overcomes the shortcomings of conventional ways of picking and displaying measurement values at fixed MTIs, by which the values truly satisfying the measurement criterion that occurs at random MTIs are often skipped. The door panels are alternately deployed into a closed position completely covering the storage cavity of the truck bed and a latch device is provided for releasably holding the door panels in the closed position. Other aspects of the disclosed technology facilitate candid photographs to be taken of users that want them. The heating cable guide strip is attached to the sub-floor by glue, nails or screws.