This is our third one of these collars. The other two were sadly broken by being forgotten when Kaiser went swimming, which he adores. Only days after our buying him a new one for these dark days - black dog; early winter nights - he siezed a chance and plunged into the river with a young friend. Great was our relief to ascertain the electronic flashing unit is now sturdily protected. Although we would not deliberately test its merit, this protects us most satisfactorily against such a common accident.