By default, the ThumbSize property is -1. If the ThumbSize property is -1, the control automatically computes its size based on Maximum, Minimum, LargeChange and related properties. If the ThumbSize property is greater than 0, it indicates in pixels the size of the thumb. Use the Mode property to specify whether the control is vertically or horizontally oriented. Use the BtnHeight property to specify the width of the buttons in a vertical scroll bar. Use the BtnWidth property to specify the width of the buttons in a horizontal scroll bar. 

You can use the ThumbSize property on 0, to allow the control acts like a spin control. The Change event occurs when the control's Value property is changed, or the user clicks the up/down, left/right buttons. The ClickPart(Part) event notifies once the user clicks a part of the control. The ClickingPart(Part) event is fired continuously while the user keeps clicking the part of the control.