Measure your pet's neck to select the ideal size. The X-Small Collar will fit a neck measuring 8-12" and is finished 1/2" wide. Small fits 11-16" finishing 3/4" wide. Medium fits 14-19" finishing 1" wide. Large fits 18-26" finishing 1" wide. The Leash is 5' long, finishing the width of choice of Collar size. The name was inspired by the scruffy, lovable dog from The Wizard of Oz.