A system for optimizing weight distribution of a golf club including a weight receiving grip, the weight receiving grip configured to be affixed to a proximal end of a golf club shaft, wherein the weight receiving grip comprises a generally tubular member comprising a shaft bore configured to surround a proximal portion of the shaft, wherein the weight receiving grip comprises a weight retention portion at a proximal end of the weight receiving grip, the weight retention portion configured to engage a weight member, a grip expanding tool configured to deflect a portion of the weight receiving grip facilitating installation or removal of the weight members from the weight receiving grip.

Embodiments of a golf club head and methods to manufacture such a golf club head are generally described herein. The golf club head generally includes at least one ball-striking face, which comprises a titanium alloy that is associated with an average grain size measuring no more than about 1 micron (μm) in the longest dimension. The golf club head is associated with a coefficient of restitution of about 0.847 or more when a ball impacts the ball-striking face.

Described herein are embodiments of golf club heads having a balance of the following parameters: a low and back club head center of gravity position, a high moment of inertia, and low aerodynamic drag. Methods of manufacturing the embodiments of golf club heads having a balance of club head center of gravity position, moment of inertia, and aerodynamic drag are also described herein.

Some embodiments include club heads having reinforced club head faces. In one example, the club head comprises a variable face thickness with thickened and thinned regions. The face includes a thinned perimeter region positioned near a perimeter of the face, and a thickened central region positioned over a geometric center of the face. The club head further comprises a 360 undercut that extends along the entire perimeter of the face. The combination of the thinned perimeter region, thickened central region, and 360 undercut reinforces the club head while permitting the face to bend. Other embodiments of related club heads and methods are also disclosed.

Some embodiments include club heads having reinforced club head faces. In one example, the club head comprises a variable face thickness with thickened and thinned regions. The face includes a thinned perimeter region positioned near a perimeter of the face, and a thickened central region positioned over a geometric center of the face. The club head further comprises a 360 undercut that extends along the entire perimeter of the face. The combination of the thinned perimeter region, thickened central region, and 360 undercut reinforces the club head while permitting the face to bend. Other embodiments of related club heads and methods are also disclosed.

A golf club head has a main body and a front recess that includes a flange. A rear portion of the main body includes a perimeter-weighting element. A striking face insert is secured within the front recess. A face center is located on the front surface of the striking face insert. A rear cavity is at least partially delimited by the perimeter-weighting element and a rear surface of the striking face insert. A rear insert is secured to the rear surface of the striking face insert. In an imaginary horizontal plane passing through a portion of the rear insert, proximate a heel portion of the club head, a heelwardmost point of the rear insert is spaced further from a vertical center plane than a minimum distance between the flange and the center plane. The club head comprises an auxiliary recess that extends outward from the rear cavity.

Some embodiments include a club head with sole mass element. Other embodiments of related club heads and methods are also disclosed.

A golf club head including a weight mount disposed on the sole, a weight member configured to reside in the weight mount, a compressible member residing between the weight member and the weight mount, wherein the weight member comprises a longitudinal axis about which the weight member is configured to rotate, the weight member comprising projections extending radially outwards from the longitudinal axis, wherein the weight mount comprises circumferential ramps, wherein rotation of the weight member about the longitudinal axis forces the projections along the circumferential ramps, wherein the weight member goes from an unlocked position to a locked position in less than one full turn of the weight member relative to the weight mount, wherein rotation of the weight member compresses the compressible member, wherein the circumferential ramps comprise detents, wherein the projections are configured to reside in the detents when the weight member is in the locked position.

Devices systems and methods are disclosed. Among other things, the devices systems and methods can facilitate ergonomic gripping of a handle; conform to the shape of a wrist; enhance golf techniques or performance; enhance racket sport technique or performance; protect a head of a user engaged in contact sports or other hazardous activities; identify concussions, in some cases in substantially real time; provide sterilization of garments; control surgical robots; allow for medical treatment of multiple subjects without disrobing; provide biometric or other data; and/or be used to train muscles or body parts for, for example, performing specified tasks using a body part.

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 head includes a body portion defining an interior cavity, a port on the body portion connected to the interior cavity, and a face portion coupled to a front portion of the body portion to enclose the interior cavity. The face portion includes a recess portion and a face plate portion. The face plate portion includes an outer portion surrounding an inner portion. The inner portion of the face plate portion configured to enclose the recess portion. The golf club head also includes a first filler material in the interior cavity, and a second filler material in the recess portion. The first filler material and the second filler material have different coefficients of restitution. Other examples and embodiments may be described and claimed.