ROHL Country Bath cartridge only for thermostatic valves A4910, A4913BO, A4917, A4817, A2917, and A4717. Please note: Test the installation before replacing the cartridge. On new installations, most cartridges have to be calibrated. This is the most common reason for replacement. On older installations, take the cartridge out and flush with high pressure. This occasionally returns an older cartridge to working condition.