The CAL3K-A is the companion to the CAL3K-AP, but with external oxygen filling. This instrument was designed for rough production environments where the automatic filling is not desired. Application: The CAL3K-A uses a combination of the Isothermal and Adiabatic calorimetry methods, while still using the dry method, i.e. it is waterless. The minimum determination time is down to 4.5 minutes.