Open-ring and pearl snaps are gripper-style snaps which have multiple "teeth" around the edges instead of a single prong in the center. Because they need to be able to self-pierce through fabric, these are not suited for tough, thick or dense material.
Size 14 snaps are 3/8" wide.
Size 16 snaps are 7/16" wide.
Pearl snaps have a 12mm pearl cap with size 16 parts.