It is made from vitreous enamel fused onto sheet steel.  Heavy gauge - weighs over a pound and, unlike modern versions, this one can't be bent easily.  Very durable.  Made in 1950s.

6" high 8" wide.

This is the real thing from a real house in real France.  Not a copy, not made yesterday.  From a house in Picardy.

Around four thousand house numbers in stock at the last count - large, small, old, high, low, enamel, cast metal, bell metal, convex, flat, Danish, French, Australian, Japanese, German, Belgian, UK.  Please let me know if this is not the number or style you require. But I have few numbers higher than #600.

Please see my other listings if you like French signs and numbers.