There are two sizing aspects to consider:
The diameter of the mouth opening. Mason jars are available in two different diameters: wide-mouth and regular. (Note: Regular jars are sometimes incorrectly referred to as narrow-mouthed jars.) FoodSaver® Jar Sealers come in both wide-mouth and regular sizes.
The volume capacity. Wide-mouth and regular mason jars are available in a range of sizes including the 4 oz., half-pint, pint and quart.