Review on Hi-Na Backyard Zipline Kit - 80ft, 100ft, 120ft - Zip Line Set for Kids Play with Seat and Handles - Backyard Ziplines for Kids - Premium 100ft Zip Line Kit - Outdoor Zip Line Play Set (80ft) by Terence Dardant

There are many other good reviews so these are just some of my thoughts. Overall: If you have two solid woods, just buy them now. Before you buy: * The sling cord is 4 feet long. Measure the circumference of the last tree/stick. I had a mature tree that was 7 feet in diameter and needed another Home Depot sling cord (3/8 inch, 9 foot steel wire sling costs $20)*. take into account if you are near the length of the line. You can lose 10 feet of wire in a thick tree (because the connector clamps also need to be away from the tree). Installation: * Everything is very simple. I had to remove the rubber boot (tree guard) on the main line to install the retaining spring (have someone hold the boot straight while you slide the line back). * Be careful with speed and turns! , as leaning up slows you down better at the end of your run. But then your starting and ending height should be higher so that the middle doesn't touch the ground. My line is quite mocking but can be too fast (see video) * Hard to get line tension, I made a tensioning system out of rope: attach to main line, carabiner on loop, wrap around tree, 2nd carabiner on loop , then rope through the first, then the second carabiner. tighten. Just pulling on the main cable is tricky, it's heavy, and zippers make it heavier too. Usage: * It's fast. watch the video My kids end up breaking the retaining spring and I may have to readjust.*Adults can use this.*Adults are faster than kids, don't start at the top! (I don't trust the retaining spring :) Also, Hi-Na's customer service is top notch. Quick and polite replies via Revain's email system.