A golf swing training device for training a user to aim a golf swing in the desired direction includes a resiliently deformable body having a top surface, a bottom surface, and a perimeter surface extending between the top surface and the bottom surface. The bottom surface is configured to support the body on a support surface, and the body is elongated along a horizontal central longitudinal axis from a first end to a second end. The body is symmetrical about a vertical central plane. There is a divot penetrating the top surface adjacent the first end coupled to a compactable, resiliently deformable ball. The body is constructed of a low-density material and is configured to abruptly decelerate when moving through a quantity of air due to an air resistance force.

Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. In one embodiment, the outer cover layer is formed from a composition comprising a thermoplastic polyurethane and polydimethylsiloxane compound. Functionalized polydimethylsiloxane compounds also can be used to treat thermoplastic polyurethane golf ball covers. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)-light stabilizers, and other additives. The coating methods have many benefits and the finished balls with thermoplastic polyurethane covers have good physical properties.

A golf ball 2 includes a main body 4 and a paint layer 6 positioned outside the main body 4. The main body 4 includes a spherical core 8, a mid layer 10 positioned outside the core 8, and a cover 12 positioned outside the mid layer 10. An indentation depth, measured when the paint layer 6 in a cross-section along a plane passing through a central point of the golf ball 2 is pressed by a force of 30 mgf in a direction perpendicular to the cross-section, is not less than 300 nm and not greater than 3000 nm. The paint layer 6 preferably has a thickness of not less than 5 μm and not greater than 50 μm.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (α/P) of a latitude α (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.

In a golf ball having a core, envelope layer, intermediate layer and cover, the (core diameter)/(ball diameter) value falls within a particular range, the core has a specific hardness profile, and the Shore C hardness relationships among the core center and surface hardnesses and the surface hardnesses of the envelope layer-encased sphere, intermediate layer-encased sphere and ball satisfy the following conditions:
core surface hardness<surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness,  (1)
(surface hardness of envelope layer-encased sphere)−(core center hardness)≥28.  (2) Also, the envelope layer, intermediate layer and cover have respective thicknesses which satisfy the condition:
cover thickness<intermediate layer thickness envelope layer thickness.  (3) This ball enables mid-level and skilled amateur golfers to achieve superior distances on driver shots and on iron shots, and moreover has a soft yet good feel at impact.

Buoyant dimpled golf ball having CoR ≥0.810, specific gravity <1.00 g/cc, initial velocity ≥250 ft/s, first aerodynamic coefficient magnitude between about 0.25 and about 0.30 and first aerodynamic force angle between about 29 degrees and 34 degrees at Reynolds Number of 230000 and spin ratio of 0.085; and second aerodynamic coefficient magnitude between about 0.26 and about 0.31 and second aerodynamic force angle between about 31 degrees and 36 degrees at Reynolds Number of 180000 and spin ratio of 0.101. Golf ball may additionally have third aerodynamic coefficient magnitude between about 0.27 and about 0.32 and third aerodynamic force angle between about 34 degrees and 39 degrees at Reynolds Number of 133000 and spin ratio of 0.133; and fourth aerodynamic coefficient magnitude between about 0.33 and about 0.38 and fourth aerodynamic force angle between about 38 degrees and 43 degrees at Reynolds Number of 89000 and spin ratio of 0.183.

In a golf ball having a core, envelope layer, intermediate layer and cover, the (core diameter)/(ball diameter) value falls within a particular range, the core has a specific hardness profile, and the Shore C hardness relationships among the core center and surface hardnesses and the surface hardnesses of the envelope layer-encased sphere, intermediate layer-encased sphere and ball satisfy the following conditions:
core surface hardness<surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness,  (1)
(surface hardness of envelope layer-encased sphere)−(core center hardness)≥28.  (2)
Also, the intermediate layer and cover have respective thicknesses which satisfy the condition:
cover thickness<intermediate layer thickness.  (3)
This ball enables mid-level and skilled amateur golfers to achieve superior distances on driver shots and on iron shots, and moreover has a soft yet good feel at impact.

A golf ball comprising a core composed of a fully neutralized polymer material is disclosed herein. The golf ball also preferably has multiple mantle layers and a cover.

A system, method and device are provided for use in golf putting training, and as golf putting training aids. The disclosed devices include particularly less-than-standard sized training balls, undersized practice balls, and smaller-than-standard diameter and/or miniature training/practice balls, constructed to have a similar weight and feel at impact as a standard-sized golf ball.

A golf ball having an outer surface with a pattern forming a polyhedron. The pattern can be flat faces forming sharp edges and sharp points therebetween. In one embodiment, the polyhedron is a Goldberg polyhedron.