A tube for a heat exchanger includes a first and a second plate portions disposed opposite each other. The identity of the one or more second communication devices is not pre-determined by the first communication device. Accuracy and reliability is achievable by calculating three kinds of reliability based on the distribution of the image characteristic quantities and then judging whether additional learning is necessary, or selecting and adjusting image characteristic quantities and estimation engine based on the reliability. A plurality of radially extending flanges is formed about the circumference of the distal end.