NOS distribution blocks are precision machined to help distribute balanced amounts of nitrous and fuel to each intake port. NOS has taken the "showerhead" design distribution block and improved it by making it from stainless steel instead of brass. This equated to a more durable, stronger distribution block that can stand up to the rigors of drag racing.
NOS has also released new distribution blocks that are used in the New Professional Fogger kits. The new blocks are made from billet aluminum and bright dip anodized red and blue for use on the fuel and nitrous sides.