This set of trickle tube constrictors allows you to slip these on the ends of your trickle tubes to reduce the flow coming out of it. Using the smallest tube size will only allow one to two kernals at a time to fall out and make the trickling much more precise and reduce the chance of over throws. With proper tuning of the unit in combination of this constrictor you can drastically reduce over throws and make your reloading process much smoother and faster.