The three-layer ball has a large inner core surrounded by a casing and a thin soft cover. The core makes up about 1.6 inches of the diameter, and the casing and cover are each about .050-inch thick.
The four-piece ball carries this design concept one step further. The center consists of a small softer inner core inside a larger more firm one. The casing and cover are similar to those of the three-piece ball.
Cores are made of polybutadiene, a hard synthetic rubber with high elasticity. The casing or mantle, which lies just beneath the cover of the ball, is made of a flexible polymer called an ionomer. Covers are usually made of a soft urethane that is formulated to be resistant to abrasion for longer wear.
The casing and cores have different hardness characteristics so the ball reacts differently when struck at different velocities. It receives more spin when hit with a wedge and less spin from a driver. The effect is more pronounced on the four-piece design.
The soft cover also grabs the grooves of the irons to increase spin and has a soft feel for shots around the green.
The premium multilayer ball delivers optimum performance on all shots and are the standard for professional players. However, while multilayer balls offer increased control for the skilled player, beginning players may benefit from the added distance two piece golf balls provide. As always, it's best to try multiple types and brands to find which ball best fits your personal game.