A pulling string apparatus of a stringing machine comprising a string gripper, a sensor, a drive element, a transmission mechanism and a control circuit; the sensor is connected with the string gripper to detect the pull force of the string gripper; the control circuit compares the detected pull force value with a pre-set value, and control the rotation of the drive element; the transmission mechanism comprises a mounting base, a sliding block, a transmission rack and a drive gear; wherein the drive gear is connected to the drive element and is engaged with the transmission rack, the sliding block arranged on the transmission rack is connected with the sensor; when the sensor and the string gripper are driven forward or backward by the sliding block under the act of the transmission rack engaged with the drive gear, the racket string will be tensioned or loosened.

A pulling string apparatus of a stringing machine comprising a string gripper, a sensor, a drive element, a transmission mechanism and a control circuit; the sensor is connected with the string gripper to detect the pull force of the string gripper; the control circuit compares the detected pull force value with a pre-set value, and control the rotation of the drive element; the transmission mechanism comprises a mounting base, a sliding block, a transmission rack and a drive gear; wherein the drive gear is connected to the drive element and is engaged with the transmission rack, the sliding block arranged on the transmission rack is connected with the sensor; when the sensor and the string gripper are driven forward or backward by the sliding block under the act of the transmission rack engaged with the drive gear, the racket string will be tensioned or loosened.

A set of racket cross-string guides which are pre-woven over a string guide holder in the same pattern used for inserting the racket cross-strings.

A set of racket cross-string guides which are pre-woven over a string guide holder in the same pattern used for inserting the racket cross-strings.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and 1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and 1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and 1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and 1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and 1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and 1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and 1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and 1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.