Attaches to most standard-width collars with elastic loops. Two loops for added stability (no more bow tie droop!) Our online DTC sales are split approximately 35% S and 65% L. Small (4.5" W x 4.5" H): for smaller dogs Large (5.5" W x 5.5" H): for bigger dogs, dogs with long fur, or small dogs looking to make a big statement Machine wash in cold water and air dry