Everyone had such great reviews for the paper holders, I thought I'd give the base a go. I only have 10 holders on top and there is NO WAY 30 would fit. I slid the trays in and they are angled much more than what appears in the Display Dynamics web page. I'm going to wait for the regular bases to come back in stock. Blah.
I own 3 of these and love them. However, there is a trick to getting the trays to stack right. But once you figure out how to stack them, they stand straight up. Don't believe the single bases were designed to hold 30 trays, maybe 15. I plan to purchase a 4th in the near future.