Diethyl silicone rubber made by introducing an ethyl group into a polysiloxane side chain has outstanding cold resistance properties, which are superior to dimethyl silicone rubber and general methyl vinyl silicone rubber. The higher the ethyl content, the better the cold resistance. However, the reactivity of the ethyl group is greater than that of the methyl group. Therefore, as the ethyl group content increases, the heat resistance decreases. As the ethyl silicone rubber used at a low temperature, it is preferable that the polymer contains diethylsiloxane chain links at 8 mol%. The operating temperature of ethyl silicone rubber is generally -70--200 ° C.