Poron is a brand name for a high performance polyurethane foam with an unique compression set. The compression set (recovery value) is many times better than rubbers at all levels of compression. Water seals with Poron can be realized with a pre-pressure of 30 till 80%. Even at the high pressures of 80%, the compression set is still relatively good compared to other sealing materials. The large range of 30-80% makes it possible to seal large variations of gaps in constructions. So if a high degree of certainty and a long lifespan is required from a seal, Poron is an excellent option.