Disclosed herein is a casting cluster for casting a body of a golf club head made of titanium or a titanium alloy. The casting cluster comprises a receptor and a plurality of runners coupled to the receptor and configured to receive molten metal from the receptor. The casting cluster also includes at least twenty-eight main gates. At least two of the main gates are coupled to each of the runners and each main gate is configured to receive molten metal from a corresponding one of the plurality of runners. The casting cluster further comprises at least twenty-eight molds. Each mold of the at least twenty-eight molds is configured to receive molten metal from a corresponding one of the main gates and to cast a body of a golf club head that has a volume of at least 100 cm.sup.3.

Described herein is a golf club head that comprises a body and a strike plate. The body comprises a heel portion, a sole portion, a toe portion, and a top portion. The strike plate comprises an outer peripheral edge and at least a portion of a strike face. Furthermore, the strike plate is welded to the body via a peripheral weld between the outer peripheral edge of the strike plate and the body. The outer peripheral edge of the strike plate comprises at least one welded portion, welded to the body via the peripheral weld, and at least one non-welded portion, not welded to the body.

Described herein is a golf club head that comprises a body and a strike plate. The body comprises a heel portion, a sole portion, a toe portion, and a top portion. The strike plate comprises an outer peripheral edge and at least a portion of a strike face. Furthermore, the strike plate is welded to the body via a peripheral weld between the outer peripheral edge of the strike plate and the body. The outer peripheral edge of the strike plate comprises at least one welded portion, welded to the body via the peripheral weld, and at least one non-welded portion, not welded to the body.

Methods of manufacturing a golf club head comprising one or more stiffening members proximate the face, and particularly solid rods or a plate with one or more cutouts, is disclosed herein. One method comprises the steps of preparing a wax mold of a golf club head including a plate stiffening member with excess material, casting the golf club head, and machining away the excess material. Another method comprises the steps of casting a golf club body, providing a plate stiffening member, providing a face component such as a face cup, tack welding the plate stiffening member and the face component to the golf club body, and welding these parts together.

Methods of manufacturing a golf club head comprising one or more stiffening members proximate the face, and particularly solid rods or a plate with one or more cutouts, is disclosed herein. One method comprises the steps of preparing a wax mold of a golf club head including a plate stiffening member with excess material, casting the golf club head, and machining away the excess material. Another method comprises the steps of casting a golf club body, providing a plate stiffening member, providing a face component such as a face cup, tack welding the plate stiffening member and the face component to the golf club body, and welding these parts together.

A shock absorbing structure of a racket contains: a head and an absorption member matingly contacting with an internal fence of the head. The absorption member is a hollowly tubular structure and covers the internal fence totally. When the head is made of carbon-fiber composite material, the absorption member is made of any one of Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head is made of metal or aluminum alloy, the absorption member is made of any one of Thermosetting Elastomers, Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head and the absorption member are made of different materials, an amplitude of the head is different from an amplitude of the absorption member, and the head interferes the absorption member, thus absorbing vibration.

An underwater training apparatus is disclosed. The underwater training apparatus may include a barrel. The barrel may contain a plurality of holes disposed across the barrel. Each of the holes of the barrel may pass through a wall of the barrel. The underwater training apparatus may also include a base funnel. The base funnel may contain a plurality of holes disposed across the base funnel. Each of the holes of the base funnel may pass through a wall of the base funnel. The underwater training apparatus may also include a handle. The handle may mechanically couple the barrel and the base funnel.

Disclosed herein is a golf club head comprising at least one crown opening and at least one crown insert attached to the body and covering the at least one crown opening. The golf club head further comprises at least one sole opening and at least one sole insert attached to the body and covering the at least one sole opening. The golf club head additionally includes at least one weight member configured to clamp first and second ledges at selected locations along a sliding weight track. The golf club head also comprise a coefficient of restitution (COR) feature located on the sole of the golf club head. The at least one crown insert is formed from a composite material having a density between 1 g/cc and 2 g/cc. The at least one sole insert is formed from a composite material having a density between 1 g/cc and 2 g/cc.

Disclosed herein is a golf club head comprising at least one crown opening and at least one crown insert attached to the body and covering the at least one crown opening. The golf club head further comprises at least one sole opening and at least one sole insert attached to the body and covering the at least one sole opening. The golf club head additionally includes at least one weight member configured to clamp first and second ledges at selected locations along a sliding weight track. The golf club head also comprise a coefficient of restitution (COR) feature located on the sole of the golf club head. The at least one crown insert is formed from a composite material having a density between 1 g/cc and 2 g/cc. The at least one sole insert is formed from a composite material having a density between 1 g/cc and 2 g/cc.

Embodiments of golf club heads, golf clubs, and methods to manufacture golf club heads and golf clubs are generally described herein. In one example, a golf club heady ma include a hollow body portion having a toe portion with a toe portion edge, a heel portion with a heel portion edge, a back portion with a back wall portion, a top portion with a top portion edge, a sole portion with a sole portion edge, and a front portion. A face portion may be coupled to the front portion and include a front surface and a back surface. The body portion includes a face support portion including a composite material and coupled to the back surface of the face portion. The face support portion may include at least one reinforcement portion. Other examples and embodiments may be described and claimed.