This is a box of empty unprimed shotshells from the Fábrica Nacional de Palencia, Palencia, Spain. It is made of aluminum and intended to be reloadable. It dates from the 1960s if I am not wrong.
The case lenght is 64 mm.
The FP logo in the headstamp was used also on early production .22 rimfire cartridges from the same factory.
The box reads:
10 aluminum cases
For small game hunting cartridge
Caliber No. 12 (18,5 mm)