+ I know it doesn't help you, but please REVIEW the product like this:
I ordered a Filbur FC-3752 filter, but received an Intex brand filter from seller "Filters Now". So far, they have shipped the wrong ones twice! 3rd party seller "Filters Now" appears to be deliberately misrepresenting their product.
This is the only really effective way to communicate to Amazon that they have a bad seller. Currently, they have NO reviews on the product. The way Amazon works, your negative review will essentially make it impossible for Filters Now to sell that cartridge on Amazon.

+ Here's their website: http://www.filters-now.com/ . I'd recommend insisting on a 100% refund, and ordering the Unicel cartridge.

+ I've added a caution note to the Filbur links. Filbur cartridges should cost the SAME or MORE than Unicels; if they don't they probably aren't real Filbur.