How to change ProgressBar color?

public class CustomPropertyGridValueElement : PropertyGridValueElement
{
    RadProgressBarElement progressBarElement;
    protected override void CreateChildElements()
    {
        base.CreateChildElements();
        progressBarElement = new RadProgressBarElement();
        this.Children.Add(progressBarElement);
    }

    public override void Synchronize()
    {
        PropertyGridItem item = this.VisualItem.Data as PropertyGridItem;

        if (item != null && item.Value != DBNull.Value)
        {
            this.progressBarElement.Value1 = Convert.ToInt16(item.Value);
        }
      
        // color progressbar indicator
        if (Convert.ToInt32(item.Value) >= 50)
        {
            this.progressBarElement.IndicatorElement1.BackColor = Color.Red;
            this.progressBarElement.IndicatorElement1.GradientStyle = GradientStyles.Solid;
        }
        else
        {
            this.progressBarElement.IndicatorElement1.BackColor = Color.Green;
            this.progressBarElement.IndicatorElement1.GradientStyle = GradientStyles.Solid;
        }
    }
}