All Zip Line Kits
When comparing backyard zipline kits, they are all the same concept: a cable (1/8" or 5/16"), a zip line trolley, a zip line brake (bungee or spring), a tightening mechanism (turnbuckle or ratcheting kit), 6 cable clips to secure either side and an attachment that connects to the trolley with a carabiner. All zip lines come with 6 foot of slack on either end of the cable for securing it to your anchors.
List: Cable, cable clips, ratchet or turnbuckle, trolley, seat or harness, and a brake. (see DIY section)
OR: buy a complete kit.