How can I flip 2d sprites in a different direction on Unity 3d?

Can someone please help me flip the 2D sprites on Unity 3D when I go behind them?

using System;
using UnityEngine;


public class CameraFacingBillboard : MonoBehaviour
{ 
public Camera m_Camera;

private void LateUpdate()
{ 
base.transform.LookAt(base.transform.position + this.m_Camera.transform.rotation * Vector3.forward, this.m_Camera.transform.rotation * Vector3.up);
}
}