A question to provideproperty

public class Marquee : System.Windows.Forms.Control
{
    #region Additional properties specific to this control: modify them in the VS properties window
    private Color sColour = Color.Azure;
    [Category("Appearance"), Description("The starting gradient color of the text.")]
    public Color StartColor
    {
        get { return sColour; }
        set 
        {
            sColour = value; 
            Invalidate();
        }
    }

    private Color eColour = Color.Gold;
    [Category("Appearance"), Description("The ending gradient color of the text.")]
    public Color EndColor
    {
        get { return eColour; }
        set 
        {
            eColour = value; 
            Invalidate();
        }
    }

    private int timerInterval = 150;
    [Category("Appearance"), Description("Controls the marquee scrolling speed.")]
    public int ScrollDelay
    {
        get { return timerInterval; }
        set
        {
            timerInterval = value;
        }
    }
    #endregion properties

// remaining class code not relevant to the question