Silicone rubber ZY-840 suitable for the production of ordinary silicone products, such as silicone rubber buttons, sealing rings, etc. Appearance translucent solid, density 1.12±0.03, hardness 40±3, tensile strength 7.0, elongation 355, tear strength 11, shrinkage 3.4~3.8, rebound elasticty 60, plasticity 155±20, vulcanizing agent double 2.5 .