Ordered a pool filter cartridge from Pool Supply World. They shipped me the wrong cartridge. Took me almost one month and a least a dozen calls to their totally ineffective customer service department to finally get a return authorization label. Still have not received a credit. These are crocked operators if you need help. You can get a return and credit from Amazon in 5 minutes so why does Pool Supply World make it so hard?. Warning: do not buy from these illegitimate frauds.