These are supports for Sterilite Boxes used to store filament. You need to print two. The dowel used is 0.6250 inches. I had some that were pretty dry and shrunken. The new dowels were s tight fit so I placed in the oven at 250 for 2 hours and they shrunk down or you can sand them. I all used 4mm heat insert to keep the dowel from moving. You may not have to to this but I had some laying around.

Boxes used.
Amazon.com: Sterilite 20 Qt Gasket Box, Stackable Storage Bin with Latching Lid and Tight Seal, Plastic Container to Organize Basement, Clear Base and Lid, 6-Pack : Pet Supplies

Dowel Used

Waddell Aspen Round Dowel - 48 in. x 0.625 in. - Sanded and Ready for Finishing - Versatile Hardwood Rod for DIY Home Projects 6410U - The Home Depot