The K-203 has been discontinued by the manufacturer. You will now need to purchase the K-202 replacement cartridge.
The Kohler K-203, K203 Aquifer Premium Cartridge is the replacement cartridge for the NSF Listed Kohler Model K-200, K200.
The K-203 is Certified by the WQA against NSF/ANSI Standard 42 & 53 Tested & Certified for the reduction of:
This Aquifer Premium refill needs to be replaced every 3-6 months depending on water quality and usage.
View Installation and Product Specifications Here