There replacement ball for the Surya X 21020L4 model it is a specific replacement component for a Surya lamp. This type of sphere is generally made of glass or translucent material, intended to replace the external part of the lamp in the event of breakage or damage. The model 21020L4 refers to a specific type of lamp, and the replacement sphere allows you to restore the aesthetics and functionality of the lamp without having to replace the entire fixture.