I believe older 87s had the metal shell. I know mine does, and it also has a vial of mercury inside. Wouldn't be suprised if it's older than I am, but it works

I believe older 87s had the metal shell. I know mine does, and it also has a vial of mercury inside. Wouldn't be suprised if it's older than I am, but it works perfectly though and I have no desire to change it. My downstairs thermostat is a digital programmable one (also honeywell). I've only lived in this place for a year, but it seemed to work fine and simply enough for programming schedules and temperatures. I only use either for heating, we don't use AC in the summer. I've seen digital ones fail over time, and this one will too. It's always a matter of "when", not "if"; but, if the cost is low enough, that may not be a big deal (assuming it doesn't cause a fire on the way out).