I purchased some smoke and flame markers for my Wings of War (now Wings of Glory) models last week. I like them.
American Wildcat pursues damaged Japanese Val dive bomber
You can have the two markers on separately, and they can be found if you click here
The smoke marker on its own
A Belgium Hurricane in trouble during the German invasion of the low countries, May 1940
They are sturdy and made from tough plastic, slotting over your altitude peg, so very easy to put on and take off.
Obviously I only intend them to be used by my Secret Wargaming Friend........................