Wristwatch electronic Shabbos

Igros Moshe (OC V #22. 25) Question Is it required to cover the buttons on an electronic watch on Shabbos which constantly shows the time even without pushing the button and is it permitted to move it on Shabbos? Answer  It is permitted to move it and the buttons do not need to be covered. The need for some reminder or cover is only for an actual fire because of concern it might be tilted to burn better. That is why there is no need for a light switch on the wall. However if you might push the button on the watch it is best to cover it or make some reminder on the button