Frozen products requiring cold insulation are housed inside of the cold-insulating container structured of a vacuum heat-insulating material, and the cold-insulating containers are loaded in a refrigerator vehicle, cold-insulating vehicle, or room-temperature vehicle other than a freezer vehicle for delivery. The toner comprises a binder resin, a colorant, and a nonionic surfactant, wherein the nonionic surfactant has an oxyethylene group and an oxypropylene group and has a ratio of the number of moles of the oxypropylene group to the number of moles of the oxyethylene group of at least 0. The well annulus contains a well fluid with a static level under static conditions. Each compacting face is outwardly convex in shape and extends continuously between two adjacent salient points. The multiplexer output thus toggles between the two programmed analog voltages at the measurement frequency.