Over the past few months we have been seeing a lot of calls on a Truth Window Hardware part marked 31878. We can confirm that that part is our part number Wi11647, the Truth Maxim Slide Shoe 11647. This piece is the part that attaches to the Truth Maxim and Truth Encore Awning Operators. The Slide Shoe attaches to the arm of the operator and is held in place by the 31879 Truth Maxim Detach Clip. The Slide Shoe slides in the Track that is attached to the sash. An Awning window is a window that swings like a one piece garage door, not to be confused by a Casement window that swings like a door.