Typically, we recommend measuring the inside diameter of the opening of the hole you wish to fill, then refer to the chart in description. Go to the top diameter column, find closest of what you measured, and go up 2 sizes. Example = Inside Diameter is 1 inch RL 10 is 1 inch for the top, so you would need a size 12. Although natural variations do exist in both size and appearance, all Dodge Cork products meet or exceed industry standards.
Grab a ruler and measure across the bottle opening/hole you need to put a cork in.
The sizes below give you the approximate hole size where the cork will sit 1/2 way sticking out of the bottle and 1/2 way in the bottle. Just be advised that corks natural material and might swell or shrink in certain environments.
So, as an example, if the opening you wish to plug is a 1/2 inch in diameter, use a #3. This will give you 1/2 in the bottle and 1/2 out.
If you want less sticking out of the bottle, use a #2.
If you want more sticking out of the bottle, use a #4.