By treaty dated 23 December 1865 France, Belgium, Italy, and Switzerland formed the Latin Monetary Union. They agreed to a combined gold and silver standard with a gold-to-silver ratio of 15.5 to 1 as established in the French Franc. One LMU Franc represented 4.5 grams of fine silver or 0.290322 gram of fine gold. Following the International Monetary Conference of 1867, the original four nations were joined by Greece, Spain and Romania. Other states later adopted the system without formally joining the treaty.
Pics of all coins in higher resolution (Obverse and Reverse).
https://files.fm/u/yfznzc37