One of the spars (spines?) bent sideways the first time I opened it, or it was broken from the factory.  And thus the auto-close feature didn't work.

Given the number of people who have left a review saying that theirs was broken on arrival, or broke very soon, I probably should have expected this.

The spines are U-shaped in cross section.  Perhaps this is stronger than the traditional hollow tubes, but I don't think so.  It probably just helps with folding.  I suspect it makes these more susceptible to breaking like this.