These are EXTRA large signature vases from Khalil Mamoon. The diameter of the opening is 3.7cm or 1.75 inches, which fits a size 30 vase gasket. However, they always vary, same as KM base grommets. If you are ordering this base and a KM grommet make your instructions clear in the comments section that you would like them to match. KM stems are all the same, it's glass and grommets that vary. .
These Jumbo Bases bases measure 12 inches in height and the diameter of the opening is 1.75 inches.