         
         var constraints: [NSLayoutConstraint] = []
         
-        constraints.append(contentsOf: self.bar.setup(leading: self.barLeading,
+        constraints.append(contentsOf: self.bar.setup(leftKnob: self.leftKnob,
+                                                      rightKnob: self.rightKnob,
+                                                      leading: self.barLeading,
                                                       trailing: self.barTrailing,
                                                       height: self.barHeight))
         

        ]
        
        return barConstraints
    }
}


    private(set) var trailingConstraint: NSLayoutConstraint = NSLayoutConstraint()
    /// Bar height constraint.
    private(set) var heightConstraint: NSLayoutConstraint = NSLayoutConstraint()
    private weak var leftKnob: Knob!
    private weak var rightKnob: Knob!
    
    /**
     Method used to setup a bar. This methods returns all the constraints to be activated.
