Choke comparison

here is the link to a good article on chokes rem870.com/2012/05/06/shotgun-chokes-explained-cylinder-improved-cylinder-modified-full/

cylinder is the choke constriction "Cylinder bore doesn’t have a restriction. Improved Cylinder has a minimal restriction. Recommended for short distances using birdshot and buckshot (20-30 yards) and self-defense. The shot pattern is much more spread out