 In practice, choke tubes tighter than "Full", such as "Turkey", are also commonly marked with but a single thin notch on the end of the tube.Hence, to distinguish between "Full" vs. even tighter chokes, such as "Turkey", it becomes necessary to measure the bore exit diameter of the choke tube to determine precisely which choke type is present among the "Full" and tighter (smaller diameter) chokes.Other specialized choke tubes exist as well.