To maintain your pet's health and well-being, regularly check your dog or cat's feeding and watering systems' parts and accessories for replacement. This Replacement Reservoir is designed specifically for use with the Deluxe Fresh Flow® Fountain, in sizes medium (50 oz.), large (108 oz.), and jumbo (216 oz.). To ensure a proper fit, be sure to match your pet's feeding and watering system with the appropriate product/item number for this replacement reservoir. A cap is not included with this replacement reservoir.