Fetch it, Tug it, Chew it! BarkBone Natural Instincts Nylon Chew Ring gives dogs options when it comes to chew time and playtime. Made for tough chewers and available in two sizes, Nylon Chew Rings are infused with allergen-free peanut butter which releases as your dog chews keeping your dog busy and entertained. Available in 2 sizes: Medium and Small. Proudly made in the USA! Made for tough chewers. Infused with allergen-free peanut butter which releases as your dog chews keeping your dog busy and entertained. Proudly made in the USA.