"Slackline is an art of dynamic balance. It is akin to tight rope and high wire but uses tubular nylon webbing." My brother Seth brought his nylon webbing (he's a slackline master) and the boys put it between two trees in our front yard. It is HARD! I didn't even get close to mastering it. By the end of the night, Geoff was able to walk from one end to another!
