Caldwell's patented Rig-Release hook is a safe and simple way to release rigging remotely, protecting workers on the job site and making lifts more efficient. You just hook the unit to your crane or spreader beam, then attach the sling(s) directly to the Rig-Release, which is designed so that it cannot release the rigging while under load when used according to operating instructions. The crane operator lifts the load, sets it, and once the crane line is slack, pulls the release rope manually or via remote control.