These Exalto wiper blades are manufactured of stainless steel 316. To prevent reflection, a black coating is applied on all metal parts. The Heavy Duty blades have a special profile that reduces lift. This makes them perfect for applications where a little more pressure is required. The Heavy Duty blades are also more screen friendly due to the use of plastic lower bridges. In case of damaged rubber, these plastic bridges will not damage the screen. H.D. blades are also available in a polished version also you can choose the look that fits your vessel. Keep in mind that every motor has a maximum blade length when choosing your wiperblade.