help needed with browser detection custom control

hi, i'm trying to write a custom server control to detect the browser being used. but visual studio is underlining the Request.Browser part of HttpBrowserCapabilities brow = Request.Browser; line of code and saying 'the name Request does not exist in the current context'

 this is the code for my control so far:-

 

 1 using System;
2 using System.ComponentModel;
3 using System.Collections.Generic;
4 using System.Security.Permissions;
5 using System.Web;
6 using System.Web.UI;
7 using System.Web.UI.WebControls;
8 using System.Web.UI.HtmlControls;
9
...