IBM System x3400 Type 7975 Installation Manual page 28

Retention tabs
Note: The bezel will also disengage from the chassis hinges if you rotate the
bezel beyond 180° or if excessive pressure is applied to the bezel. Do
not be alarmed because this is how the bezel was designed. The bezel
is designed with breakaway hinges so that you can easily reattach it to
the chassis.
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System x3400 Types 7973, 7974, 7975, and 7976: Installation Guide