Size #2 shutters

It looks like only Compur #2 shutter exists. I did not find other makes of this size.

It has a bit strange cell thread.

Their main dimensions are:

• Front lens cell thread: M45.75x0.75
• Rear lens cell thread: M45.75x0.75
• Rear mount thread: M50x0.9
• Lensboard hole diameter: 52.5mm