Name: Deborah Michigan (Zone 6a) Community gardens rock!
I checked the Q & A section for the four shelf (sturdy, aluminum) package on Home Depot. Those shelves are listed as able to fit in all Palram greenhouses including, specifically, the Oasis.
Fan of Winter Sowing, dahlias, heirloom tomatoes, community gardens, natives & Douglas Tallamy's Homegrown National Park