It is made from vitreous enamel fused onto sheet steel.  Heavy gauge.  Unlike modern versions, this one can't be bent easily.  Very durable.  Made in 1970s.  The white enamel is in relief, giving excellent definition.
5" high 7" wide.
This is the real thing from a real house in real France.  Not a copy, not made yesterday.  From a house in Loire.
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.
UK shipping free of charge.  Elsewhere £7.
Please see my other listings if you like French signs and numbers.