ToolPanelRef is used to refer to the upper tool panel or lower tool panel in a Dashboard panel. 

Autodesk.AutoCAD.Customization.ElementBase
    Autodesk.AutoCAD.Customization.VersionableElement
        Autodesk.AutoCAD.Customization.ToolPanelRef

Public Class ToolPanelRef
Inherits VersionableElement

public class ToolPanelRef : VersionableElement;