The 9141S controller automatically increases fan speed for cooling the block and decreases fan speed at your setpoimt for maximum stability during calibrations. This gives you quick response without sacrificing measurement performance. Heating and stabilization time within 12 minutes, and the 4 inches deep to minimize stem effect when calibrating long probes. Connect your thermal switch, fuse or cutout to the special binding posts on the back panel of the calibrator and start your heating cycle. The display locks in the temperature that triggers the themal switch.