Harmsco Calypso Blue HB-10-20-W Cartridge 10" 20.0 Micron (8 pack)Application: 10 inch big blue cartridge 20. 0 micron Please note this item is sold in minimum quantities multiples of 8. Please also note that the price shown is per cartridge, not per case. Features include: Pleated design means more surface area and better holding capacity They can be washed and re used in most applications down to the 5 micron size Thermally bonded end caps ensure better sealing Each cartridge is individually shrink wrapped NSF