CRASH PAD - Like the Three Bears...
Upholstery foam rubber is way too soft.
SFI shock absorbing foam is way too stiff.
The material in The CRASH PAD Tested BEST to absorb Spinal Compression Forces in a crash.
The SFI foam works great for elbow, arm, knee, leg, or other narrow rounded surface.
That's what it was made for.
BUT the seat bottom is very different.
The surface area under your butt is much larger and the material needs to have the right compression resistance and not bounce.
Nothing works better or even close to the material in The CRASH PAD to
Reduce your Risk of Spinal Injury in a crash.