See the chart below to determine the correct Adapta-Capô needed for your bottle. The neck size is measured in millimeters (mm) from the outside edges of the threads.
*Size F is for a longer-neck bottle.
You can do this either by measuring the top of the bottle with a ruler or tape measure that is marked in millimeters, or, if you don't have either, you can compare the neck to regular U.S. coins to determine the size.
To measure with a ruler, first take the camp off of your bottle to expose the bottle's threads. Second, measure the distance between the outside of the threads on the opposite sides (shown above).
If you are using a US coin to determine the bottle's neck size, first, remove the cap from your bottle to expose the threads. Second, line up one edge of a coin with one of the outer edges of the threads on your bottle. Third, use the chart below to help determine what size the neck is on your bottle.