Warrant officers are specialists, comprising only 8% of the officer corps. Warrant officers hold warrants from their service secretary and are specialists and experts in certain military technologies or capabilities. The lowest-ranking warrant officers serve under a warrant, but they receive commissions from the president upon promotion to chief warrant officer 2. They derive their authority from the same source as commissioned officers but remain specialists, in contrast to commissioned officers, who are generalists. There are no warrant officers in the Air Force or Space Force.