I don't own one so I wouldn't know for sure whether it's a solid state controller or a bimetallic strip, but I'm guessing they went with the primitive bimetallic strip technology as the electric Q's have a warning about not using the temperature controller when it's -25c outside.Pretty sure it would be an SSR (solid state relay, an electronic switch) and I've never been able to whack one of those hard enough to get it working, although it did make me feel better afterwards.