The MediCordz Headset Kit is used to increase neck strength and mobility through forward and lateral flexion, extension and rotation exercises. The MediCordz Headset Kit comes with a head harness with four attachment points, a 2ft/60 cm modular tubing with 1.5 - 4.5 lbs (0.68 - 2.0 kg) of pull, and a door mount. Note: Headset should fit snugly around head. Choose smaller size if in-between sizes. Small: 19.6" - 21.2".