Unity3D Unlit/Transparent (Alpha) Shader

Shader "Unlit/Transparent (Alpha)"
{
 Properties
 {
   _Alpha("Alpha", Range(0,1)) = 1
  _MainTex("Texture", 2D) = ""
 }
 
 SubShader
 {
     Tags {Queue = Transparent}
     ZWrite Off
     Lighting off
     Cull Back
     Blend SrcAlpha OneMinusSrcAlpha
     
        Pass
        {
         SetTexture[_MainTex]
         {
          ConstantColor(1, 1, 1, [_Alpha])
          Combine texture, texture * constant
         }
        }
 }
}

C# Using delegate event

 public delegate void EventHandler();
 public event EventHandler LoadCompleted = null;