SimPure Y7T-C Filter Replacement Kit6 Month Kit: 1x CF filter, 1x RO filter, 1x CTO filter 12 Month Kit: 2x CF filter, 2x RO filter, 2x CTO filter Compatible with SimPure Y7T Series Only ALK and CTO filter elements can be used interchangeably 3s Replacement, No Disassembly: Replacement can be completed within 3 seconds with a single twist, and no need to use any tool. We are providing you with the easiest way to install without disassembly.