I am currently installing CO detection in MA in hotels and I am using one of the technical options of which I am using technical option F. I have been using a CM15a co detector manufactured by 3M and I was informed that this would not meet the requirement of the technical option F as the activating point is not 50 PPM. Does anyone know of a UL approved CO detector that is 24v wall mount with a NO/NC contact that will activate at 50 parts per million.