Convenient, that is, if you have a 1 inch diameter finger!
I prefer an over-sized tube which I can line with felt to just about grip. And do remember that hands can swell. There is nothing worse than trying to do a quick puppet change only to have a finger firmly stuck in the head.
But if you have slender Les-like digits then the tubes he mentions are very strong, as are carpet roll cores which are excellent for making pillars on the marionette stage, which is quite a different website.