SP-SB-RING is a swivel tightening ring for securing smartphone or tablet holders to 17mm ball pedestals. This includes only the 17mm tightening ring. No holders or mounts are included in this package. This tightening ring is compatible with 17mm ball mounts and helps keep smartphone or tablet holders such as The Mobile Grip 2 Universal Smartphone Holder (MG002), Slim-Grip Ultra Universal Smartphone or Midsize Tablet Holder (SM060-2), or Slim-Grip Universal Tablet Holder (TAB001) secured to mount pedestals. Arkon 17mm ball mounts include Models GN079 (Windshield or Dash Sticky Suction Mount Pedestal), GN057 (Air Vent Mount Pedestal), CM088-G17 (Seat Rail or Floor Mount Pedestal), or GN112 (Friction Dashboard Mount Pedestal with Safety Anchor).