The collars are made from ethically sourced leather in Kenya. The collars are hand-beaded by Maasai women artisans from my Village in Kajiado. The hardware is hand-cast from 100% recycled brass. TO MEASURE CORRECTLY Wrap a string around your dog's neck. Mark the string and then measure the length of it with a ruler or tape measure. Remove your dog's current collar and stretch it out flat. Then measure from the center of the buckle to the current sizing hole or adjustment being used. If you are not sure about the Sizes please Contact us before making the order and we will be more than happy to assist you with sizing.