Active thermostating is key in predicting storage times under certain conditions, since sorption isotherms can differ significantly at different temperatures. Thus, it may not be possible to recalculate aW for other temperatures.
In addition, the temperature control range should be similar to the conditions that will affect the product during storage or use.

In the case where it is sufficient to carry out measurements at ambient temperature and with a prepared sample, you can purchase the device at a more attractive price.
In addition, such devices are lighter, with smaller dimensions and can be used as portable meters.