using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class Item

    {

        public int Id {get;set;}

        public override bool Equals(object obj)

        {

            var item = obj as Item;

            return item == null ? false : this.Id.Equals(item.Id);

        }

​

        public override int GetHashCode()

        {

            return this.Id.GetHashCode();

        }

    }

    public static void Main()

    {

        var master = (new []{ 1, 2, 3, 4, 5}).Select(x => new Item {Id = x});

        var update  = (new []{ 1, 3, 5}).Select(x => new Item {Id = x});

        master = master.Intersect(update);

        foreach (var item in master)

        {

            Console.WriteLine(item.Id);

        }

    }

}