To maintain your pet's health and well-being, regularly check your dog or cat's watering systems' parts and accessories for replacement. This Replacement Strainer is designed specifically for use with the Petmate® Fresh Flow® Fountain. The medium size fits both the 50 oz. and 108 oz. fountain, while the jumbo size fits the 216 oz. fountain. To ensure a proper fit, be sure to match your pet's watering system with the appropriate product and item number for this replacement strainer.