Two channel type data loggers: TR-71S comes with two temperature channels and TR-72S is equipped with 1 humidity channel and 1 temperature channnel. The compact, lightweight design coupled with a long battery life and easy-to-use software makes this series the foundation of our Thermo Recorder line. The product is an all-in-one package that includes the data logger unit, sensor and software; just connect it to your computer and it is ready to use.