For optimum results, your HMP45C Temperature/Relative Humidity sensor should be recalibrated annually. If you’ve found it inconvenient to rewire a replacement sensor to your datalogger while the original is being recalibrated, the HMP41 is for you.
The HMP41 is a removable sensor head that is compatible with any HMP45C sensor. Simply "unplug" the sensing element of the HMP45C and replace it with an HMP41. Given this, one or two spare sensor heads can facilitate scheduled recalibrations over an entire network.