This is a little spacer that stabilizes stacked 4oz canning jars. I know it fits Ball brand, plain finish, 4oz. I have not tested it with other brands or the quilted/decorative kind. Without these spacers, these jars stack surprisingly poorly, as the jar base is just slightly larger than the hole in the ring.Use ABS if you want to put these in a dishwasher. After printing, clip off the anti-peel tabs and the tiny support risers that come up from them. I use a small pair of sharp diagonal cutters, as it helps the part break nicely between the layers at the smallest spot. Clipping those off will reveal little feet that hook under the inner lip of the lid ring to keep the spacer with the ring.