Mask of Constraint Development Materials A material used to break through weapons, ascend Resonators, and upgrade skills.

A mask worn by Fractsidus recruits. It seems to be used to suppress the rejection reaction induced by the integration of Tacet Discords. The side effect that comes with it is the suppression of the wearer's normal human emotions. Perhaps, that's one of the designer's purposes?
Sources
Synthesis - Transposition
Drop: Fractsidus