Traditional Culture Encyclopedia - Hotel reservation - What door does HHM-2 stand for?

What door does HHM-2 stand for?

A sealed door representing the reinforced concrete threshold. HHM2 sealed door is a kind of door that can increase air tightness, where H stands for life threshold and M stands for air tightness. It is characterized by no threshold at ordinary times, which is convenient for people or vehicles to pass, and the threshold is quickly set in wartime to meet the requirements of protection and sealing.