All Silverline stacks and stack components are made from high-quality stainless steel, which offers superior quality and durability. Plus, Silverline Stainless Steel Stacks are available in a choice of finishes?mirror polished stainless steel or its new and exclusive automotive finish grade, Midnight Black. The 6"x36" black stacks are available in angle cut or the new 30-degree AUSSIE style turn-out. The 8"x36" black stack is available with the popular and aggressive 45-degree angle cut.