A refill bag equals about 60 grocery bags. The refill is easy to replace and can last up to two months for one cat. Results may vary. Other types of bags cannot trap bacteria and odours, making them less hygienic. The plastic film of the refill has not only five layers, but is unique on the market because it is designed with the Air-Seal technology. All the features of this product provide a quality refill, which the normal bag cannot possess.