1" Shank, Interchangeable Tool Torque Hitch Ball, For With 1- 7/8" & 2" Balls, This Single Hitch Ball Works With Both Of The Most Popular Size Couplers, The Ott-1 Tool Torque Feature Needs Only 1 Wrench To Tighten The Hitch Ball To The 1 Tool Torque Ball Mount, This Eliminates Damage To The Hitch Ball During The Installation.