Based on this product's specifications, here are some alternatives and similar models
FF RT2 Temperature Sensor for RT-823 Thermostat
Summary description:
The FF RT2 is a dedicated temperature sensor designed for use with the F&F RT-823 temperature controller. This probe ensures accurate temperature monitoring and reliable data transmission to the regulator, enabling precise climate control in various residential or industrial applications. It is built for seamless integration with the RT-823 system to maintain optimal thermal conditions.