Does anyone know where I can get flexible 4" DC tubing with the smooth inside - I thought Penn State but its not in the new catalogue. I tried to search the forum but must not have the right keyword.
Most flexible DC tubing is smooth with ridges for reinforcement wire. I am sure Penn State still has it. Some of the #s are Do83,n-J13-o415 and N-CVD-415
I thought I saw some that was described as "smooth interior wall for better airflow" I envisioned a liner or something that was smooth on the inside so the ridges didn't appear on the inside of the tubing
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