This 120-Volt a.c.-powered (with 9-Volt battery back-up) carbon monoxide (CO) detector includes an LCD display that reports the parts per million (PPM) of CO detected. However, this readout--and, thus, its added cost--may be deemed unnecessary by some consumers, given manufacturers recommend taking emergency measures in the event of the alarm sounding, no matter if the level detected is 70 PPM or higher. On the other hand, some homeowners could find it useful to note "pre-alarm" levels as indication of possible problematic conditions developing. Self-diagnostics enable the device to keep tabs on its own functionality. A memory mode that stores the highest level of CO detected is useful in instances where household members have been away for a time. In addition to a "test" button on its face, the design of the system allows triggering the test mode via most household (i.e., TV or VCR) remote controls--although, again, a consumer may not find this feature worth the extra cost. The unit's alarm seems as loud and at the same pitch as competitive offerings. If the back-up battery power level becomes low, or the battery is not in place, a distinct alarm code sounds and "bat" (short for battery) flashes on the LCD display, as will the power light.