Adele ring. In mathematics, the adele ring (also adelic ring or ring of adeles) is defined in class field theory, a branch of algebraic number theory. It allows one to elegantly describe the Artin reciprocity law. The adele ring is a self-dual topological ring, which is built on a global field.
Water softeners are built to last for at least 10 years. When properly maintained, the softeners can last several years beyond that time.
I read somewhere once that a water heater typically lives for abotu 11 years. However my parents had the same one for over 21 years and had no trouble until the end. We use tankless water heaters which conceptually should last almost forever as long as the water is not hard or you descale them regularly.