My apt complex didnt have right size filters. Having been a home owner for many years, Ive always changed my own filters. I decided to purchase since they couldn't tell me when they may have the right size. These filters were the right fit. The complex uses the fiberglass disposable. I dont ask maintenance to change my filters. Could be a while before they would come, I just do it myself. I purchased the 6 pack & changing them out every 90 days or less will last me a while. Im hoping to see a difference in my electric bill. Fingers crossed :hand_with_index_and_middle_fingers_crossed: