Sorry for the multiple replies but I didn’t see your reply to my post about the Westclox unit until now. I will try to get a pic of it when I am there next month as Im only at the food market once a month. I will have to ask too if I can get a pic of it too. I am going to mention I have a big time interest in vintage smoke alarms and I am pretty sure they would understand. Im also going to mention to them that it should be replaced and if they do save the alarm for me. If it is an AC unit it will be my second AC unit. I have a Nortron unit that is also AC. No date code that I can find but my guess is it was made between 1977 and 1980 since the unit has a brass horn. This westclox unit looks exactly like the battery unit except it has a light in the middle. The alarms in away resembled speakers and were bulky. The Westclox units were popular in Canada in the mid to late 1970s and even the very early part of the 1980s. Nowadays they are impossible to find even on ebay. Just like the Dicon unit from around the same era that Fire Alarm Fan’s Oster smoke alarm is based on.