# | Crystalyx Rolyx-Pro Mag
CRYSTALYXÂ® RolyxÂ® Pro-Mag is a dual-purpose, low-moisture block, formulated with added protein and magnesium. It is designed to be self-fed to cattle and horses consuming moderate to good quality forages, fescue forages, low magnesium forages, or forages with high potassium concentrations that interfere with magnesium absorption. It is energy dense and highly fortified with trace minerals and vitamins. CRYSTALYXÂ® RolyxÂ® Pro-Mag also contains RABONÂ®, the proven-effective oral larvicide, to prevent the development of horn flies, face flies, house flies and stable flies in the manure of treated animals. CRYSTALYXÂ® RolyxÂ® Pro-Mag contains chelated/organic trace minerals.