Anti-Submarine ? I say anti-aircraft bomb fuze, specifically for the 20 Kg Bomb (Bomba da 20 c. V.), identified by the truncated cone junction.
"750" are the meters of fall before the explosion, "1" is the identifier of this delay.
There are 8 variant of this fuze, numbered from "1" to "8": the No. "1" was activated after 750 meters, the No. 8 after 400 meters.
Every number identify a step of fifty meters between 750 and 400 meters.
This fuze could act as point detonating, the arming occurs after a fall of approximately 40% of the number indicated on the fuze (i.e. No.1/750 is armed after 288 meters of fall)
20 kg and 3 kg AA bomb were dropped in groups of 8, each with a different fuze setting, to occupy an airspace of 350 meters, which was useful to compensate for sighting errors.
Regards
stecol