Are you talking pore size or bead/pellet size? Those make a difference too.. I'm assuming you're wanting to use them in your humidor so here goes:
For what it's worth, I'm using 3 angstrom beads in about 2mm size and 4 angstrom beads in about 1mm size.. ordered them for my sons medications (he has many..) a while back, the leftovers I conditioned to 65% RH and they work like a charm in my coolers. Took a couple days of experimenting overnight with sponge in a tupperware box but it sure was worth the hassle I have to say. With this post I'm also expecting people to jump on a ***** train as to why I'm playing lottery with my cigars and why didn't I purchase a "proven" pre-fabricated product etc..
As to which pore size you should use.. I'd say both 3 and 4 angstrom would work since Ammonia is 3.6 angstrom, Carbon Monoxide is 2.8, Water is 3.2 etc. remember that it's not just water you want to pick up but stinkies too.. That's why it has its name "Molecular Sieve" it's because it won't let anything in the pores as they literally don't fit into the pores on a molecular level. I'm sure you know all this but I figured others might want some insight too. Good luck with your quest, I'm going to bed.