KONG refillable catnip toys utilize top quality, natural North American catnip. These toys have a special compartment that can be opened and closed, so that fresh catnip can be added again and again - to last all of your cat's nine lives. Catnip is a natural, non-addicting herb that encourages play in about 70% of cats, who have an inherited gene that compels them to respond to catnip. For utmost kitty enjoyment, gently twist the filled toy to release catnips' herbal oils. To maintain maximum freshness, freeze extra catnip until needed. Watch your kitty toss, flip, kick and enjoy their new KONG catnip toy. Your cat will love you for it.