AD 56419440 Blade Hopper Neoprene for Nilfisk Advance. Neoprene is used in cases where the standard duty tan gum blades won't hold up and distort. Neoprene blades are naturally chemical and oil-resistant and can be used in food processing plants, chemical plants and areas where tan gum blades might be affected by chemicals. They are also naturally chemical resistant and can be used where caustic chemicals exist. Priced Each. Replaces Nilfisk Advance 56419440. Our Part Number AD 56419440