This non-tilt block and tackle channel balance is constructed of a mill-finished steel U-frame housing. The internal working components include a spring, cord and pulley system, but the plastic top and bottom guide shoes must be selected separately as they are not included with the balance itself. These window counter balances are used to counter-weight the moving sash on single and double hung vinyl windows. If your windows (sashes), are having problems staying up when opened, it may be that your sash balances or hardware needs to be replaced. The sash balances hold the weight of the window pane, over time, the springs can wear out or fail. Replace your sash balance for a smoother operation of your window and allow fresh air to enter your home with a window that stays open.