(38 cm) wide under FIL rules. The sidewalls of the head may not be more than two inches (5 cm) tall. Pocket The pocket of the head is where the ball is carried and caught. It consists of interwoven string attached to the head. Traditional stringing with leather strings interwoven with nylon has declined in popularity in favor of synthetic mesh stringing. Mesh is typically made of nylon and comes in a variety of diamond configurations, which can affect the pocket's throwing and retention characteristics. The typical mesh pocket uses four main nylon strings to affix the mesh piece to the head: a topstring, two sidewalls, and a bottom string. The topstring is often made of a slightly thicker string, in order to resist the abrasive forces that come from scooping the ball up. The sidewalls are used to affix individual mesh diamonds to the sidewall holes on the sidewall of the head. The sidewalls have the most effect on the pocket's performance, as they dictate the placement of the pocket in the head, the tightness of the channel of the pocket, and even the pocket depth. The bottom string is used to fine-tune the pocket depth, and serves to keep the ball from slipping through the bottom of the pocket. In addition to the four strings used to affix the mesh piece, shooting strings are woven through the diamonds of the mesh in order to help fine-tune the pocket's characteristics. They can either be made of typical nylon string, or a hockey style lace. Shooting strings are often used in straight, U, or V shapes. They serve to increase the pocket's hold on the ball, as well as fine-tune the way the stick throws. They can act to change the tension of various portions of the pocket, helping to create a "ramp" for the ball to roll along as it exits the pocket. As of the 2013 season, the NCAA has passed a rule stating that shooting strings are limited to an area within a 4-inch (10 cm) arc drawn from the top of the plastic of the scoop. This essentially eliminates U- or V-shaped shooting strings, as they almost always cross below the 4-inch (10 cm) line. The pocket depth is governed by rule as well. When the ball is placed in the deepest point, the top of the ball must not be below the bottom of the