We went to Grigsby Appliances when we were unable to locate filters for our heat pump anywhere else. Their selection was absolutely amazing. We had tried every major home improvement store, grocery store, etc. with no luck. We walked into Grigsby's and they had every size, shape and style available. Granted, we did pay more than we would have, but I can't say if that was due to the unusual size or just that their prices are higher overall.