The Window Source of San Francisco casement windows swing outward to a full 90 degrees for maximum ventilation. A multipoint locking system closes the unit tightly from a single lever making the casement the most energy efficient of all operable window styles. Casements may be joined together into double, triple or quadruple units.

Replacement casement windows are an excellent choice for hard-to-reach areas like above a kitchen sink or in a projecting window such as a bay or bow. The single crank operator can open and close the window with ease.