What do you mean by "characteristics?" The purpose is to keep the back of the chair from making marks or 'dinging' walls which they may be pushed against.
The material and design is anything anyone desires. Typical dimensions and design of chair moulding is approximately 2 1/4" wide, 1/2" thick, with 'OG' curves on each edge.
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We have met the enemy and he is us . . . Walt Kelly
I'm guessing from your previous posts that your interest is in injection moulding parts for this chair. Can you explain a bit more what you are asking?
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I didn't have a really important life, but at least it's been funny (Lemmy Kilminster 1945-2015)