* Challenger is the registered trademark of Challenger, the manufacturer of Challenger brand drinking water system filtration equipment.  The replacement water filters and reverse osmosis membranes listed above are not manufactured or endorsed by Challenger  Rather, these replacement filters and RO reverse osmosis membranes are manufactured by other companies.  While these filters and reverse osmosis membranes are compatible for use in Challenger under counter reverse osmosis water filtration equipment, we make no representation as to whether using these water filter cartridges and RO reverse osmosis membranes is consistent with the warranty and specifications applicable to Challenger under sink drinking water system equipment.