The Airtight Hangar Door block is a 1x3x1 block that can be opened and closed, designed to be used in groups to create large entrances to hangar bays where ships can enter and exit, while still being able to contain oxygen when closed.
When open, the block takes up 1x1x1 in size. When closed, it extends to 1x3x1, sealing off two blocks worth of additional space. Two can be placed opposite each other, leaving a gap of four blocks as an entrance when opened. Any number can be placed in a row, giving you an opening of 4 by any size as a maximum hangar bay opening without resorting to more creative measures or mods.
- The airtight door while closed is certainly airtight, it seems to have no oxygen when standing in the 'cube space' whatsoever. That is if a character stands directly next to the door in the same 'block' with it while closed, the character will suffocate as if they were in a completely unpressurized room.
- The base block of the door despite never moving is no longer air tight when the door is opened, despite being a fully solid block. This is most clearly seen on the default Red Ship that spawns on Easy Start 1, opening any side hanger door will instantly depressurize the internal 'control station' deck.