Blast door

A blast door is a type of door. It is an important safety lock for UNSC ships. Blast Doors are similar to Airlocks in that they are used to seal off areas suffocating, or have a strong possibility of suffocating a breach and loss of atmosphere. They are distinguished by their interlocking sections that rise from the floor, and drop from the ceiling. The Blast Doors have large panels of what seem to be high-strength plexi-glass, since it can resist blasts of plasma from the handheld Plasma Rifle.

Trivia

 * On the, the blast doors were also used to trap Covenant boarding parties. This is an efficient way of cutting off boarding parties, as the doors are built to be extremely resilient to damage.