"enclosure" refers to a system that allows for the control of volume without requiring the addition or subtraction of stops. in a two-manual organ with great and swell divisions, the swell will be enclosed. in larger organs, parts or all of the choir and solo divisions may also be enclosed. the pipes of an enclosed division are placed in a chamber generally called the "swell box". at least one side of the box is constructed from horizontal or vertical palettes known as "swell shades", which operate in a similar way to venetian blinds; their position can be adjusted from the console. when the swell shades are open, more sound is heard than when they are closed. sometimes the shades are exposed, but they are often concealed behind a row of facade-pipes or a grill.