A golf club head including a striking face, a back portion, and a back cover attached to the back portion, wherein the golf club head includes damping structures and materials to achieve desired acoustic characteristics.

Distance display systems and methods are included which may be used to display an accurate range from a cup of a golf hole to a plurality of tee hitting positions.

A golf club has a first shaft coupled to a club head, a second shaft configured to slidably engage a portion of the first shaft, a grip coupled to the second shaft, and an adjustable length shaft assembly received by the second shaft and configured to allow a portion of the first shaft to slide in relation to the second shaft in a first configuration, and to restrict a portion of the first shaft from sliding in relation to the second shaft in a second configuration. The grip is restricted from rotation about the first shaft or the second shaft as the first shaft slides in relation to the second shaft.

Systems and methods for sensing and monitoring various athletic performance metrics, e.g., during the course of a game, a practice, a training session, training drills, and the like, are described. These systems and methods can provide useful metrics for players and coaches relating to athletic performances in various sports, including various team sports.

A golf club head comprising two components, wherein the first component comprise a ball striking surface, a striking face return, and a sole extension with a rear mass. And wherein the second component comprises a lower density material, comprising part of the crown and part of the sole. The first component comprises a majority of the mass of the golf club head, having a rear mass comprising 20% to 35% of the mass of the golf club head.

A golf club head that includes a body defining an interior cavity and an exterior surface, the body including a face disposed within a forward portion and extending between a toe and a heel, a sole defining a bottom portion of the golf club head, and a crown defining a top portion of the golf club head. The golf club head further includes a front weight assembly having a first weight removably secured with a first fastener and a second fastener, the front weight assembly being disposed forward of a head center of gravity. The first fastener is disposed on a heel side of the front weight center of gravity, and the second fastener is disposed on a toe side of the front weight center of gravity.

Systems and methods for measuring the concentricity of golf balls using varying energy levels to gather and analyze data on concentricity.

A golf club head includes a club body and a resting face angle adjuster. The club body includes a crown opposite a sole, a toe end opposite a heel end, a back end opposite a face, and a hosel. The sole includes a sole surface. The resting face angle adjuster includes an adjustment member having a keel surface, and a recess formed in the sole such that a portion of the sole surface at least partially bounds the recess. The adjustment member is disposed in the recess and positionable between a first adjustment position and a second adjustment position. In the first adjustment position, the keel surface is at a first distance relative to the portion of the sole surface. In the second adjustment position, the keel surface is at a second distance relative to the portion of the sole surface not equal to the first distance in the direction.

A method of producing a golf ball applies ultrasonic welding on two half shells to form at least one intermediate layer, at least one cover layer, or at least one intermediate layer and at least one cover layer. The ultrasonic welding may include pressing the two half shells together, delivering a high power electrical signal to a welding stack, and converting the high power electrical signal at the welding stack to ultrasonic energy. The converting may include converting the high power electrical signal into a mechanical vibration, modifying an amplitude of the mechanical vibration to generate a modified mechanical vibration, and applying the modified mechanical vibration to an interface of the two half shells to weld them together ultrasonically. Aspects also relate to golf balls, or one or more layers thereof, made using ultrasonic welding.

A method is provided for preventing back injuries related to sport motions or swings that includes setting an attachment height of a distal end of an elastic of a warmup and training device, the attachment height set to define an angle α backwards from vertical above center of a practice motion specific to a sport to be practiced, attaching a handle to a proximal end of the elastic where a type of the handle corresponds to the sporting activity to be performed, performing the practice motion while holding the handle and stretching the elastic, and returning to the beginning of the practice motion to repeat the activity.