The cardboard tube that PC uses is "industrial strength". I've stood and bounced on it without being able to put a dent in it. I normally use a saw to cut it open. However all of the damaged masts I've seen looked like they were run over by something while in transit. I've refused to take delivery on both PC and Hobie masts because of damages incurred in transit.
Industrial strength is an understatement. When mine came I had to cut up the tube with a chainsaw to throw it out. The tube is much heavier than the mast. Of the 3 mast I have had shipped to me over the years, two of them were damaged in transit, one was damaged by the fork of a forklift, and the good one that made it, the mast was undamaged, but the tube was toast. I will say the that the packaging (industrial strength tube) plastic wrap, styrofoam support, etc. was very well done. The shippers are hard as hell on everything.
