The drag link in your steering system connects your pitman arm on your steering box to the steering knuckle or tie rod. As you move your steering wheel, the pitman arm moves, and thus allows you to steer your Jeep.
If you've installed larger wheels and tires, don't forget to upgrade your drag link as well, so you can be sure it will be up to the job of turning those larger tires. A factory sized link can bend or break under the strain of steering larger tires.
