The silicone used in building our vascular models has a shore hardness range of 37-39, a tear resistance of 21 N/mm^2 (120 ppl), a tensile strength of 6.3 N/mm^2 (920 psi), a maximum elongation of 340 percent, a specific gravity of 1.08, an elastic modulus of 3.1-3.4 (450-500 psi), and our silicone is transparent with a refractive index of 1.41. Some models use alternate silicones, please refer to the technical sheet for specifications.