You're correct. I poked around to see what they were like and found this: https://www.ebay.com/itm/134131981597 https://www.ebay.com/itm/134131981597 Adjuste

You're correct. I poked around to see what they were like and found this: https://www.ebay.com/itm/134131981597 https://www.ebay.com/itm/134131981597 Adjusted for inflation this would cost almost $500. Probably explains why the ones in my bungalow starter home were just bimetallic coils with mercury switches.