Version: 2018.1
public RectTransform handleRect ;

Description

Optional RectTransform to use as a handle for the slider.

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when Using UI elements.

public class Example : MonoBehaviour { public Slider mainSlider; //Reference to new "RectTransform" (Child of "Handle Slide Area"). public RectTransform handleHighlighted;

//Deactivates the old Handle, then assigns and enables the new one. void Start() { mainSlider.handleRect.gameObject.SetActive(false); mainSlider.handleRect = handleHighlighted; mainSlider.handleRect.gameObject.SetActive(true); } }