If you need more space, simply add on the Flex Extender, which can be twisted onto any Flex Capsule to give you room for extra product (1.43 oz., to be exact—which means for carry-on travel, you'll want to attach it to size medium or below to stay under the liquid threshold). The Bestseller Set features five medium-sized capsules, two small ones, and one flex extender. To solve this problem, Cadence launched the Adapters, which can be added to the top of a capsule so that product pours, drips, or splashes out.