Both the Duoflex and the Duoflex Ultravision are vaguely based on the M59 facepiece, but the differences are quite notable. The exhale valve is placed in the front, and there is no voice diaphragm. The harness is made of rubber instead of fabric and is attached differently to the faceblank. The oral-nasal cup is completely different, as it resembles much more the US design.
The faceblanks are made of black rubber and have a peripheral seal. They have the following parts attached:
An exhale assembly at the front of the mask, made of plastic. The valve is a simple rubber disc attached with a stud. The cover has the Pirelli logo on it
An inlet assembly, with a DIN thread and either a black or beige inlet valve
An oral-nasal cup, with two inlet valves and attached to the mask by being wedged onto the interior part of the exhale assembly
A rubber 5-straps system, attached to the mask differently on each variant
Two eyepieces, different on each variant
Exhale valve cover
Inlet assembly with black valve
Inlet and exhale assembly from the inside (without the oral-nasal cup), note the brown inlet valve
The Duoflex, the earlier of the two variants, was a bit simpler and cheaper than the Ultravision. The eyepieces were triangular, coloured black and crimped much like the M59. The strap system was attached directly to the faceblank using rubber studs.
The Duoflex Ultravision was slightly more expensive than the normal Duoflex. The eyepieces were much larger and they were secured to the faceblank using screws on the blue plastic parts. The strap system was attached to plastic buckles that allowed for an easy replacement.
The Duoflex and Duoflex Ultravision were sold with any filter required for the job, they could be also issued with fresh air breathing apparatus equipment and other setups that required a facepiece with an exhale valve.
A duoflex with an ammonia filter
A duoflex ultravision with an organic vapours filter