ARKON's SPHDMAGKIT magnet mount kit includes everything you need to convert a 17mm ball mount into a magnetic phone holder mount. SPHDMAGKIT was specifically designed for larger or heavier phones that require extra magnetic hold. The kit includes a 2" x 1.88"diamond-shaped magnetic mount head with tightening ring and 2 adhesive metal plates (one round, and one rectangular). Attach the magnetic mount head to any 17mm mount ball head and secure with the tightening ring. Adhere one of the included metal plates to the outside of your device or case. The mount's built-in magnet head powerfully attaches to the metal plate, keeping your smartphone or other device secure without using a holder.