linuxmanxxx wrote:...so why use anything between it and the foam?
Tensile strength, maybe?

I didn't look at the spec.'s, but while a hard shell might give impact resistance, there might not be much tensile strength. Long fibers, such as cotton or FG threads, give tensile strength. We need both of these properties, not just one.

Again, I didn't bother to look at the spec.'s; it might be in there somewhere.