I'm building this class to download files in parts/sections/segments. In .NET 4.0, I can use this code to specify the range to download from long startPos = int.MaxValue+1; HttpWebRequest.AddRange(startPos); and it works because there is a long overload for the AddRange method. When I looked up the .NET 3.5 version, I realised the AddRange() method allows using int only. The possible workaround would be using the AddRange(string, int) or AddRange(string, int, int) methods. Since the class will have to work in .NET 3.5, I'll have to go with the string specification but unfortunately I can't