Choosing riding gear doesn't have to be a chore. We've streamlined the choices so you don't have to. If you have a zip line where a fall could result in injury, grab a harness. In order to connect the harness to the trolley, you need a lanyard and a carabiner. If your zip line is close to the ground, a seat is a great choice. You will need a carabiner to connect the seat to the trolley.