Seals with water flow become porous and cracked after several years. Then they can no longer fulfil their task, become leaky and let water through. You should replace the seals at the latest when the time comes. The set contains standard sizes and reliably seals threads. It is best to replace the seals before they become cracked. Seal assortment rubber Contents: 4x 3/8", 4x 1/2", 2x M22x1, 2x 3/4", 2x M24x1, 2x M28x1.