PK Aqua 2 PCS Threaded water filter catridge-9'' prefilter cartridge for RO/Aquaguard - Threaded Type Model Spun for Outer Filter Water Purifier 2 Pcs - Threaded water filter catridge-9'' prefilter cartridge suitable for RO/Aquaguard - Threaded Type Models. Threaded Filter;RO-Pre Filter;Aqua guard Compatible;Pre-filter;1.. Effective Threaded PP Spun Filter -0.5 Micron Catridge for removal of all Sediment / Sewerage Contamination from Public Common Water Supply. Compatible for all Aqua Guard Model with threaded Pre Filter for Removal of Sand,Dirt,Worm,Contamination.... To achieve good quality Drinking Water from your Water Filter System, Recommended to change the Pre-Filter Cartridge for every two to three months to protect the water from Worm, Sand, Dirt, Contamination.Pack Contains 2 nos of 9" aquasfilters pre filter cartridge compatible for RO/AquaGuard RO Water Filter Systems. Compatible for all Aqua Guard Model with threaded Pre Filter. Sleek Cartridge ,OD of 180 MM and Very Suitable for 250 MM Bowl.