What do a rescue helicopter and your ballfield backstop have in common?

Beacon Athletics | Harken

Beacon Athletics + HarkenAvalanche on the North Slope. Several possible victims. You’ve got to fly through 80 MPH wind gusts to get to them, then hold ’er steady while you lower the litter. It better go like clockwork.

What’s the name on the pulley that keeps the rope taut and true?