System Support (console application with C#)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication2

{
    class Inventory

    {
        string[] productNames = new string[100];
        string[] productModels = new string[100];
        string[] manufacterNames = new string[100];
        int productID;
        string productName;
        string Model;
        string Manufacture;
        string CPU;
        int CPUType;
        string RAM;
        string RAMType;
        string HDD;
        string ODD;
        string VGA;
        string Description;
        int quantity ;

        int n = 0;

        public void Add()
        {
            Console.Write("Enter Product Name : ");
            productNames[n] = Console.ReadLine();
            Console.Write("Enter Product Model : ");
            productModels[n] = (Console.ReadLine());
            Console.Write("Enter Manufacter : ");
            manufacterNames[n] = (Console.ReadLine());

        }
        public void file()
        {
            for (int i = 0; i < n; i++)
            {
                string[] lines = { productNames[i], productModels[i], manufacterNames[i] };
                System.IO.File.WriteAllLines(@"WriteLines.txt", lines);
                Console.ReadKey();
            }
        }
        public void Search()

        {
            Console.Clear();
            Console.Write("\n Select your hardware: \n \n 5.MainBoard \n 6.CPU \n 7.Hard Disk \n 8.Ram \n * Back (Press ESC) ");

      Console.ReadKey();
        }

        public void Print()
        {

            for (int i = 0; i < n; i++)
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine(" Product Name = " + productNames[i] +"\n Product Model =" + productModels[i] +"\n Manufacture =" + manufacterNames[i]+"\n");
                Console.ResetColor();

            }

            Console.ReadKey();
        }
    }
    class users
    {
        int userID;
        string userName;
        string password;
        bool loginstatus;


    }
    class Menu
    {
        int choice;
        public int Show()
        {
            Console.Clear();
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.SetCursorPosition(20, 0); Console.WriteLine("Welcome To System Support");
            Console.SetCursorPosition(18, 1); Console.WriteLine("Developers: XX");
            Console.ResetColor();
            Console.WriteLine();
            Console.Write("Please Enter Your Choice: \n\n\n 1. Add New Product \n 2. Search Product  \n 3. Print Product List \n 4. Save \n 5. Exit \n ");
            Console.WriteLine("------------------");
            choice = Convert.ToInt32(Console.ReadLine());
            return choice;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Console.Title = "System Support";
            Menu menu = new Menu();
            Inventory productList = new Inventory();
            int choice;
            do
            {
                choice = menu.Show();
                switch (choice)
                {
                    case 1:
                        {
                            productList.Add();
                        }
                        break;
                    case 2:
                        {
                            productList.Search();
                        }
                        break;
                    case 3:
                        {
                            productList.Print();
                        }
                        break;

                    case 4:
                        {
                            productList.file();
                        }
                        break;

                }
            } while (choice != 5);






        }
    }



}