Herm Sprenger Dynamic RS Vienna Double Jointed Bithelps to create more control over strong horses that evade a contact extremely versatile offers 4 different rein options depending on where the reins are attached, varying degrees of lever action intensify the riders aids using a curb strap can limit the poll pressure and additionally acts onto the lower jaw ideal to master technically difficult passages in showjumping courses Ring: 50mm Thickness: 16mm