If your canister filter is leaking, the culprit may be the sealing ring. We offer convenient two-packs of Eheim Double Tap Unit Sealing Rings for Eheim canister filters. Use the replacement rings to fix a leak or replace the sealing rings as part of the filter's regular maintenance routine. For the best results, sealing rings should be replaced yearly to avoid the potential for a leak and to prolong the life of the filter. Eheim Double Tap Unit Sealing Rings are sold in two-packs. The rubber rings are extremely durable and have a rounded body for easier installation.