This dog bandanna comes in different sizes. The collar can slide thru the opening of the bandanna which can be created to the size of the collar width. The bandanna is cotton fabric and sewing with either cotton thread or poly cotton blend thread. The sizes are extra small, small, medium, large, and extra large these measurements are based on the length of the bandanna length and height. The bandanna comes to a triangle point and the general opening for the bandanna is 1 inch wide, if you need the opening smaller or wider please email with your order number at the time of purchase to have the opening adjusted to fit your dog’s collar. Please make sure you measure the size of the parachute clip to allow the collar to slide thru.