Grade H (Heavy Cutting and Impact Application): This cover rubber has the characteristics of reducing the severe wear caused by the conveying material when conveying sharp and abrasive objects. For example, metal ore (mining), limestone (mining), granite (mining), quartz, blast furnace clinker, slag, crushed metal ore, sandstone (mining), stone chips, slate, coke (cold), crushed Glass and grit. Grade D (Heavy Wear Application): This cover rubber, by experience, is suitable for conveying large abrasive materials as defined under various conditions. Grade L (General Application): This cover rubber is suitable for conveying moderately abrasive materials such as lumps, sand (sharp), superphosphates (clumps or powders), bone, coal (open-air), ash (ashes), quicklime, cement (furnace); mildly abrasive (transport), non-abrasive and dry (material), e.g. sand (smooth), cement (floor), clay (clay), slaked lime, charcoal, Cereals (grain), vegetables, fruits, flour, dry flour (inert), wood chips and pulp (dry).