The Trifecta takes the basic Ultra ThinLine Half Pad to a whole new level. The cotton base design creates a wither profile and spine free channel, allowing the Ultra ThinLine to lay on either side of the spine so that it is always in the right place. ThinLine developed this pad to give riders the fashion appeal of a sheepskin half pad and the shock absorption they and their horses need without the bulk, high maintenance, or cost of a full sheepskin pad . The Trifecta offers no interference for riders who prefer close leg contact with their horse. Sizes Medium (measures 18" between the rolls and 23" including the rolls) and Large (measures 19 1/4" between the rolls and 24" including the rolls).