What special feature is shared by the following phrases?

OPEN-ENDED
SPACE CADET
STRETCH RUN
STAGGERED START

Answer:

Each phrase is self-descriptive. In OPEN-ENDED, the word ENDED is "open(ed)" by the intervening letters: opEN-enDED:

spaCe cADET - CADET is "space(d)"
stRetch rUN - RUN is "stretch(ed)"
STAggered staRT - START is "staggered"

Credit:
Joseph Appel
(after Matt Ginsberg)

Note: See Matt Ginsberg's puzzles posted 11/10/18 and 11/23/18.