Tough 130cm (50″) Ultimax Therapy Ball is manufactured seam-free and extra tough with smooth walls. Two-ply roto molding makes them highly uniquely strong, but perhaps the most amazing thing about these balls is that the top ply is transparent. Wear and tear is limited to the top clear layer, a layer that is easily cleaned. The right metallic color always stays vibrant. The Ultimax Therapy ball is light green ( in photo).