The module is typically used in applications like photovoltaics. Onto the glass of the window module, a platinum ring electrode has been sputtered, which acts as a counter electrode (CE). The top electrode of an ordinary sensor acts as working electrode (WE). The reference electrode (RE) is placed in the outlet flow path. The window allows optical access to the WE. The standard configuration includes Viton O-rings, but this can be upgraded to Kalrez to enable work with more harsh chemicals.