using System;

using System.Web;

​

public class Program

{

                public static async void Main()

                {

                                var item_string = "ZKM08F-BD-FA/1K78";

                                var double_encoded_item_string = HttpUtility.UrlEncode(HttpUtility.UrlEncode(item_string));

                                Console.WriteLine(double_encoded_item_string);

                }

}

​