It only takes two trees and the spirit of adventure to start zipling in the back yard all while riding a just a few feet off the ground. Follow the directions and your zipline will be set up in 30 minutes. Series Kit Zip Spring provides an easy end to an exhilarating ride. Our extra long 5.25’ long powder coated steel spring is made for use all of our Slackers Ziplines. The rubberized stoppers at each end protect the line, the trolley and the rider with a smooth finish.