A type of CI that is less significant (in some senses, from some perspectives) than a Prime Item, but more important than a Non-complex Item. In the MIL-STD-490 framework, this class of CI had its own Specification (Spec) format (the “B2” specification) along with explicit rules for when it should be used. The specification was typically written by the Prime Contractor, and authenticated at PDR. The design of the Critical Item was often (but not always) accomplished by a subcontractor.