This Tripod Mount Ring is designed for Tamron 100-400mm F/4.5-6.3 Di VC USD (Model A035), It features Arca-compatible dovetail which allow you attach your lens to Ball Head, Clamp or Panorama Head of Arca-Swiss standard. The Anti-slide bottom can prevent your lens from accidentally slipping out of the quick release adapter, Security screws and hex wrench are included for free.