This extra large V-shaped transfer opening makes sure you will have the maximum and smoothest air passage area. The middle support bridge divides the transfer port into a dual hole port. This middle bridge makes sure the pellet or slug nose cannot fall into the enlarged transferport hole, but will be guided smoothly by the middle bridge into the barrel. This set also includes our high flow, stainless steel pinprobe. Together, this set will give the maximum airflow behind the projectile.