Medal for Voluntary Service in the Free French Forces
Medaille des Services Volontaires dans la France Libre

Instituted 4th April 1946 for those who had volunteered to serve in the FFF prior to 1st August 1943.  The medal is a 40 or 36mm high silver plated cross of Lorraine. the obverse bears the inscription  FRANCE LIBRE  and the reverse bears the dates  18 JUIN 1940  8 MAI 1945
The two commonly encountered versions are below, the second is the smaller type with a cross height of 36mm .