USB 2.11 is a compact, unitized, single spring, elastomer bellows design mechanical seal. It can fit EN 12756 (DIN 24960), ISO 3069, and ANSI B73.1 M-1991. Positive key drive via drive bands protects bellows from torsional strain. Generally used for many water-based applications, such as wastewater treatment, pulp and paper, food processing, marine, and other general applications.