Notice
Magnetic constrictors are parts of a Federation starship that are used on warp cores and deflector dishes. (VOY: "Caretaker"; Star Trek: First Contact)
In 2371, when the USS Voyager was pulled into the Delta Quadrant by the Caretaker, Captain Kathryn Janeway ordered that the magnetic constrictors be shut down to avert a warp core breach. (VOY: "Caretaker")
In 2373/2063, the crew of the USS Enterprise-E learned that the Borg were attempting to transform the ship's deflector dish into an interplexing beacon to attract more Borg from the 21st century for reinforcements. Captain Jean-Luc Picard ordered the separation of the secondary dish by disengaging the magnetic constrictors. (Star Trek: First Contact)