Notice for die longevity: Never strike a die with a metal hammer. Always use a rubber or composite mallet for hole punching or setting grommets or fasteners. A steel hammer strikes such a severe blow that the metal in the dies absorbs the entire shock and begins to crystallize. This crystallization begins to weaken the dies, which will become brittle and fail prematurely.
This special die quickly sets the ventilators. Merely punch your hole, set the ventilator with the neck up on the base, and then slip the fabric and washer in place, a few even taps with a mallet will set the vent.