Many homes have staircases that aren't bordered by a wall. In this situation the Y Spindle aids installation of the pressure mounted gates to these types of staircases. The Y Spindle wraps around the baluster to provide a secure installation. On the Gateway (Model G11), use Y Spindles only on the hinge side of the gate. No more than 2 per gate can be used. On the Center Gateway (Models G15 and G35), the Y Spindle can be used on either side of the gate. However, they must be used on the same side. No more than 2 per gate can be used. NOTE: For installation of a pressure-mounted gate on a staircase with balusters on both sides, you will need to use a K10 Installation Kit.