It goes by many names… contrabbasso ad ancia, contrebasse à anche or simply reed contrabass. This strange item is not a brasswind, but a woodwind. It does look a bit like an ophicleide and was used in bands like a contrabassoon.

This instrument normally has seventeen keys. These include five for the left hand and five for the left thumb. Then there are five for the right hand and two for the right thumb. Unlike other woodwind instruments, with the contrabbasso ad ancia, each note can be produced by opening just one tone hole. There are no alternative fingerings for specific notes and trill keys are not present and not needed.  Here’s a link to a page about the instrument with a fingering chart.

This contrabbasso ad ancia was made in Italy by Luigi ALZIATI. He established his musical instrument workshop in 1870 and achieved great success. Following the two World Wars, the company was sold off to the Bottalis. Yet, his descendants managed to restart the family tradition and the company exists again today, repairing instruments. 

It seems that it was made for a music shop and this is featured on the stamp. Prof. Giuseppe Li Pera was a musical instrument shop in Reggio, Calabria which also still exists today. 

It is made of nickel-plated brass. All parts are present and original to the instrument.