The Boomerang is a remote controlled trolley return system designed for zip lines built over terrain that makes it inconvenient to return the trolley to the origin point. If you're planning on building a zip line that runs over water, rough terrain, or sits too high for a regular trolley walk-back, then the Boomerang is for you.  The Boomerang is designed for zip lines with a 6% slope or less.  Soaking wet zip lines can impact the Boomerang's ability to travel up the line.  Best when used in dry weather. The Boomerang is not designed to carry a passenger up the zip line.  Max weight is 10lbs when the motor is moving the trolley up the line. The Boomerang is patent pending.   Want to see how it works? Check out our product overview video!     Need replacement parts?    - Battery - Charger - Drive wheel   If you're not happy, send it back for a full refund within one year.   Commercial Use: Call us 1-888-476-3701