- they help tamper proof the cassette.
        - provide an area that information can be written regarding the cassette.
        - help prevent air leaks.

Incorrect application of shrink seals can cause more problems than it solves.

The shrink seals come in a liquid that helps maintain the seal in a "loose" state, after the seal is installed and allowed to dry, the seal shrinks and conforms around the object the cassette.

This liquid, if allowed to remain on the seal, can seep into the cassette via capillary action.

Liquid seeping in the cassette can alter the weight of the filter that the cassette contains and/or alter the filter's chemical composition, both events are undesirable.

It is therefore imperative that the seals be rid of excessive liquid when they are installed.

A proven way to perform this task, is to get several sheets of paper towels (Bounty has proven to be most effective) and place, a handful of wet shrink seals flat on the towels. Cover the seals with more paper towels and tamp dry. Use towels as needed to achieve drying.

Proceed to mount the seals treated in this manner on cassettes.

Repeat the process with another handful when you use up the first quantity. It is recommended that you proceed in small quantities. Discard any excess seals. Do not replace unused shrink seals in the container that they came from.

Shrink seals take about 120 - 150 minutes to dry depending on ambient relative humidity.