I had a few different sized clear plastic props back in the early sixties. No strength. They liked to shed blades during a run, even without a ground strike. The only good thing I found with them is they let you see the stress cracks as they form. I don't recall that they were any harder to see while running than the white Top Flite plastics, just not as strong.

After the second prop not only threw a blade from an .049 while bench running in my back yard, but stuck in the wood siding of a neighbors house 20' away, I broke the rest up and threw them away.