Properties of PolyUrethane that make it a good choice for intravascular catheters include its high biocompatibility and relative non-thrombogenicity. Comparing similar French sizes, PolyUrethane has a greater inner diameter than Silicone due to its high tensile strength and thinner wall. Initial stiff, it is easy to insert and advance, especially in small sizes, but it will soften once in the body. PolyUrethane must be EtO sterilized.