Head First C# Code: Chapter 11
Baseball with Callback
BallEventArgs.cs

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

namespace _1_Baseball___with_callback
{
    public class BallEventArgs : EventArgs
    {
        public int Trajectory { get; private set; }
        public int Distance { get; private set; }
        public BallEventArgs(int Trajectory, int Distance)
        {
            this.Trajectory = Trajectory;
            this.Distance = Distance;
        }
    }
}