Comfort Collars let your pet rat, ferret or guinea pig walk in style! This fashionable pet accessory is made from a unique material that is stretchy for safety and cottony for comfort. The attached Furry Friend Finder Bell helps you locate curious critters. The Stretchy Stroller Leash, sold separately can be attached for a safe, indoor walk. The medium Comfort Collar is adjustable from 7.5 - 9 to provide a cozy fit for your critter.7.5 - 9 Adjustable