Each of the two berthing ports on "Destiny" contains a hatch. Both hatches are normally open, and remain open unless a situation arises requiring a module to be isolated. Each hatch has a window. The hatches can be opened or closed from either side. The hatches have a pressure interlock feature, which prevents the hatch from being opened if there is a negative pressure across the hatch (higher pressure on the outside of the hatch). The hatch openings are a square like six sided shape - which is associated to that module.