File with two classes that implement StopWatches

AutoStopWatch.cs

// Reference:
// https://stackoverflow.com/questions/3903222/measure-execution-time-in-c-sharp
// Answer by https://stackoverflow.com/users/435383/katbyte

using System;
using System.Diagnostics;
using System.Threading;

namespace Diagnostic
{
    public class AutoStopWatch : Stopwatch, IDisposable
    {

        public AutoStopWatch()
        {
            Start();
        }

        public virtual void Dispose()
        {
            Stop();
        }
    }

    public class AutoStopWatchConsole : AutoStopWatch
    {

        private readonly string prefix;

        public AutoStopWatchConsole(string prefix = "")
        {
            this.prefix = prefix;
        }

        public override void Dispose()
        {
            base.Dispose();

            var format = Elapsed.Days > 0 ? "{0} days " : "";
            format += "{1:00}:{2:00}:{3:00}.{4:00}";

            Console.WriteLine(prefix + " " + string.Format(format, Elapsed.Days, Elapsed.Hours, Elapsed.Minutes, Elapsed.Seconds, Elapsed.Milliseconds / 10));
        }
    }

    public static class AutoStopWatchUsage
    {
        private static void Usage()
        {
            Console.WriteLine("AutoStopWatch Used: ");
            using (var sw = new AutoStopWatch())
            {
                Thread.Sleep(3000);

                Console.WriteLine(sw.Elapsed.ToString("h'h 'm'm 's's'"));
            }

            Console.WriteLine("AutoStopWatchConsole Used: ");
            using (var sw = new AutoStopWatchConsole())
            {
                Thread.Sleep(3000);
            }
        }
    }
}