Review on Harken - Overhead Garage Storage Hoist for Cargo Box, Self-Leveling & Safe Anti-Drop System, Simple One-Person Operation, Smart Organization for Garage by James Pfettscher

Read them over and over again, for they are not the most logical or conveniently worded instructions you will encounter. Also remember that if your rafters have 24 inch centers, 6 foot risers cannot be drilled on the ends. Their support department replied to my email that three bolts would suffice instead of four, but that was after I went ahead and bought a second set of 2x6s cut to 6.5 feet. However, once installed, the system works quite well.