Not every production run justifies ceramic grain pricing. The YS 549+ is the specification for fabrication shops and engineering facilities running mixed-metal work — steel, high-carbon steel, titanium, non-ferrous — where production volume makes cost-per-belt the governing decision, not peak performance. Treated aluminium oxide grain raises the bar on standard ALO: harder crystal, later to glaze, more material removed before the belt needs changing. Y-weight polyester, semi-open coat, wet and dry.