ESL 445CT Fire Alarm Smoke & Heat Detector Test

[@willbill808]

The 4 digit sticker printed on the inside is the date code. First two digits are the year of production. My old house came with an '87 model. The older ones like that did not have the heat collector dish; they had the older style button. Black base indicates one made in the late 80s. The very first and very last of them had white bases.