Epion describes a group of reactive specialty polymers with a backbone made of polyisobutene. Moisture cure and addition cure (hydrosilylation) types exist. When compounded and cured, the sealants impress by their outstanding barrier properties against gases and moisture. Where such characteristics are sought-after, Epion is the right choice. By nature, Epion systems are at least two-component. The price of the polymers is considerably high so that mass applications cannot be approached.