I have been trying to find the Firestone Air Lifter Bags but they are on backorder, enter the spring spacers as a temporary solution.
One thing to point out, we installed these on a non Plug-in Prius and installation was easier. On my Plug-in Prius, the springs are alot stiffer since the Plug-in has a heavy battery in the back.
This means, installation was definetly easier on a non Plug-In Prius.
Now… my rear cargo carrier does not scrap when going over steep incline driveways!
One thing to point out, you need one spacer kit per wheel!