... cracks,no air bubble,no impurity11 Sample for free Features of Silicone rubber rings:• Non-toxic and Pyrogen free raw ... anti-aging, high temperature, water, etc. better Advantages for Silicone rubber rings:1. Excellent sealing2. odourless, tasteless and non-toxic3 ... has good flexible, and good stability Disadvantages for Silicone rubber rings:Not suitable for use with concentrated acids and bases, ...