Patent ID: 8663024

Claim:
A device that provides a particular human-perceptible stimulus to a golfer when the golfer is holding a grip portion of a golf club with both of the golfer's thumbs extending along a shaft of the golf club, the device being configured to provide said particular human-perceptible stimulus only when a shaft-to-forearm angle δ between a centerline of a forearm of the golfer and a shaft of the golf club is at a predetermined value substantially between 145 degrees and 160 degrees, wherein said device has an interface that can be held in contact with a particular portion of a golf club, wherein said device is configured such that said stimulus is provided at a time when said interface is in contact with said particular portion of the golf club, wherein said particular portion of the golf club is the grip of the golf club, wherein said interface has a curved surface with a varying arc radius, and wherein said device includes an inter-finger element that is attached to said interface and that is so configured that the inter-finger element can extend between adjacent fingers of a hand of the golfer when the golfer is using that hand to hold the curved surface of the interface in contact with the grip of the golf club.