The opening is quite large & you cannot fit a 30 gallon plastic bage inside. I tried. I did not want to put out the money for contractor bags as I really feel that they would not work either. You could always put a plastic bag in a garbage can and pour the leaves into the bag that way. The material on these bags is light & there is a wire rim around the front opening. I think I have 3 sets now. I just keep filling them. I really like them.