Palm Springs HydroJet Inflatable Lid

What part is this a replacement for?
The Lay-Z-Spa Palm Springs HydroJet inflatable lid is a direct replacement for the inflatable part of the lid.
Why do i need an inflatable lid?
An inflatable lid is essential to providing insulation to your Lay-Z-Spa. This helps to maintain water temperature when the spa has been switched off. It also helps to speed up the heating of your Lay-Z-Spa.
It's important to note that the lid should be placed inside the cover before inflating.
This lid can also be used with the Palm Springs AirJet Model.