The Microline Clack S3069 O-Ring is an essential component in your filter housing. By replacing your o-ring after every three filter replacements, you ensure that your o-ring will not suffer deterioration that could cause leaking and water damage. If you notice water leaks coming from your unit, check the o-rings and inspect the sumps as well. Replace the o-ring if it appears damaged. The strength of this rubber gasket keeps the housing sealed shut, providing you with clean water without the hassles and headaches of potential puddles, dampness or mold.