This listing is for 2 sets of cartridges with 2 filters in each set. They are still sealed in plastic as shown in pictures. The filter cartridges are designed to fit all types of pools and brands using type D filters, each with a capacity of 2 weeks.

Measuring 4.13 in X 3.75 in, this modern filter cartridge is compatible with all universal/all brands. It is easy to install and use, and you'll love how it keeps your pool or spa water clean and fresh. Made in Mexico, the Summer Waves TYPE D Swimming Pool Spa Pump Filter Cartridge comes with no manufacturer warranty and is perfect for those who want to maintain their pool or spa without the hassle of changing filters frequently.