// le proprietà che servono alla pagina
page.ProductID = requestContext.RouteData.Values["ProductID"].ToString();

public class ProductRouteHandler : IRouteHandler
{
  public ProductRouteHandler(string virtualPath)
  {
     this.VirtualPath = virtualPath; 
  }

  public string VirtualPath { get; private set; }

  IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext)
  {
     IProductPage page = BuildManager.CreateInstanceFromVirtualPath(VirtualPath, typeof(Page)) as IProductPage;

     // le proprietà che servono alla pagina
     page.ProductID = requestContext.RouteData.Values["ProductID"].ToString();
     // Dal compilatore ASP.NET ottengo la pagina vera
     return BuildManager.CreateInstanceFromVirtualPath("prodotto.aspx", typeof(Page)) as IHttpHandler;
  }
}

protected void Application_Start(object sender, EventArgs e)
{
   RouteTable.Routes.Add("productsRoute", new Route("prodotto/{ProductID}", new ProductRouteHandler("~/prodotto.aspx")));
}

e.InputParameters["CodArt"] = ProductID;