Pirelli produced the Penna respirator from 1923 to 1931, when it was replaced by the M31 gas mask.

The Penna was initially fitted with the Type A filter (similar to the small box respirator filter; probably because the Italian army used the SBR during WW1) and later, with the M31-M33 brown filter, used by the army and fire brigade.

In 1933, the M33 and T33 gas masks were produced, the latter for the use of firemen and the civil defence corps. That same year, the RMF33 gas mask was produced by IAC for use by the navy.
In 1935, the T35 was issued to the army and for civil protection ( UNPA – Unione Nazionale Protezione Antiaerea) until 1945. Also that year, Pirelli produced the RMF35 for the navy.

In 1939, the optical Italian 1939 model for tank crew and artillery operators was produced. It was made of natural grey rubber, but was re-issued in cheaper synthetic rubber two years later.

Usually on the left side of Italian T35 gas masks near the name of the mask, are marks which refer to the year of production. The photograph shows 1935 and four dots, signifying 1935 + 4 years = 1939.

Italian factories making gas masks in the 1930s and 40s were:

Spasciani (still in business)
Pirelli
IAC
Sacic
Superga

Navy masks: RMF33, RMF35, RM3
Front-line army masks: M31,M33, Penna and T35
Used by second-line troops: T35