Disclosed is a swimming assistance apparatus, which is worn on a user's both feet to provide the user with buoyancy, such that the user can float on water and swim in a good swimming style while repeatedly moving the waist from side to side like a fish, thereby reinforcing the user's waist muscles. Persons who have knee joint arthralgia or backache or persons who have disability in the lower body can use the swimming assistance apparatus for medical purposes, such as pain relief or treatment.

A golf club includes a golf club head having a body defining an interior cavity. The body includes a sole, a crown and a skirt positioned around a periphery between the sole and crown. A face defines a forward portion of the club head and includes a striking surface width and a hosel defining a hosel bore. A channel and a recessed port are positioned in the sole. The channel extends substantially in a heel-to-toe direction. A sleeve is mounted on a tip end of the golf club shaft and is adapted to be inserted into the hosel bore. A fastener has a shaft portion extending through a passage and a head portion located in the recessed port. Selectively attaching the sleeve adjusts at least one of a loft angle and a lie angle of the club head.

A golf club includes a golf club head having a body defining an interior cavity. The body includes a sole, a crown and a skirt positioned around a periphery between the sole and crown. A face defines a forward portion of the club head and includes a striking surface width and a hosel defining a hosel bore. A channel and a recessed port are positioned in the sole. The channel extends substantially in a heel-to-toe direction. A sleeve is mounted on a tip end of the golf club shaft and is adapted to be inserted into the hosel bore. A fastener has a shaft portion extending through a passage and a head portion located in the recessed port. Selectively attaching the sleeve adjusts at least one of a loft angle and a lie angle of the club head.

A golf club includes a golf club head, a shaft adapter secured within a hosel of the golf club head, and a shaft secured within the shaft adapter. The golf club shaft is formed from a fiber reinforced polymer and extends along a longitudinal axis between a tip end and a grip end. The golf club shaft includes a tip end section, a grip end section, and a tapered section between the tip end section and the grip end section. The tapered section of the shaft includes a reference portion within the upper half that has a frustoconical shape with a near-constant taper rate, and a narrowed portion within the lower half. The narrowed portion is recessed relative to a reference surface extrapolated from the frustoconical shape.

Disclosed herein are various embodiments of a golf club head having improved mass distribution characteristics. The golf club head includes a body and a face positioned at a forward portion of the body. The golf club head also includes one or more mass elements positioned at predetermined locations about the head. The mass elements assist in achieving a desired relationship between the moment of inertia about a center of gravity x-axis and the moment of inertia about a center of gravity z-axis.

An aerodynamic golf club head producing reduced aerodynamic drag forces. The club head has crown section attributes and material attributes that impart beneficial aerodynamic properties and performance.

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.

A sports ball may include an interior bladder and a cover disposed about the bladder. The cover comprises a plurality of adjoining panels, wherein each panel defines a plurality of panel edges that each extend in a predetermined edge direction along an edge length of less than 7.5 centimeters. The cover may further define a plurality of interior channels. Each interior channel extends in a predetermined channel direction along a channel length of less than 7.5 centimeters. The panel edges and the interior channels are staggered, such that each edge direction is obliquely angled with respect to each of the other edge directions, and each interior channel direction is obliquely angled with respect to each of the other interior channel directions and each of the edge directions of the respective panel. Such an arrangement limits directional feature length and promotes a balanced topography upon the exterior surface of the ball.

An artificial shuttlecock, a feather and a preparation method thereof are provided. The feather includes a connecting portion, a first portion, a second portion and a concave. The first portion and the second portion are disposed on the opposite sides of the connecting portion. The concave is located at an outer edge of the second portion. The concave is formed by the following steps of: defining an overlapped outline, which is the outline of the adjacent feather overlapping on the second portion; defining a reference point, which is a point where the overlapped outline is closest to the connecting portion; defining a shifting reference line, which passes through the reference point and is parallel to the connecting portion; defining a reference outline, which is located outside the shifting reference line; and cutting the reference outline to form the concave.

A golf club head comprises a body having a face, a crown and a sole together defining an interior cavity. The body having a channel located on the sole and extending generally from a heel end of the body to a toe end of the body. A weight member movably positioned within the channel such that a position of the weight member within the channel is able to be adjusted, thereby adjusting a location of a center of gravity of the body. Additionally, adjustment of the weight member provides a maximum x-axis adjustment range of the position of the center of gravity (Max ΔCGx) that is greater than 2 mm and a maximum z-axis adjustment range of the center of gravity (Max ΔCGz) that is less than 2 mm.