Alpha component of the color.

	var color : Color = Color.white;
	color.a = 0;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public Color color = Color.white;
    void Example() {
        color.a = 0;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public color as Color = Color.white

	def Example() as void:
		color.a = 0