or cast-iron sash weight or counter-weight concealed within the window frame. The sash weight is connected to the window by a braided cotton sash cord, or a chain, that runs over a pulley at the top of the frame, although spring balances are sometimes used. Repairing a broken cord requires disassembling parts of the window frame.

The term "sash windows" is used interchangeably with the term "box sash windows" in the United Kingdom, and frequently used to describe