Transponder

The transponder comprises a transponder body and a folding air bag, the transponder body is arranged on the folding air bag, and the folding air bag is provided with an inflation connector used for being connected with an inflation assembly, or the transponder further comprises the inflation assembly which is connected with the folding air bag so as to inflate the folding air bag. The inflation assembly is capable of automatically inflating when meeting water. After the transponder falls into water, the inflation assembly can automatically inflate the folding air bag, so that the transponder body can suspend on the water surface and provide signals for the search and rescue radar, a search and rescue ship can conveniently find people falling into water in time, and the inflated folding air bag is easily found by the people falling into water and provides supporting protection for the people falling into water. The physical loss of people falling into water can be reduced, and the practicability of the transpo