OUFRO

• Production era - 19??-19??
• Code number - 16469
• Type - Extension ring for 35/50mm M-bayonet and 280mm telyt lenses with 1:1 ratio or stacked for greater magnification per Forum discussion [1] below
• Source
  • Dennis Laney's Leica Accessory Guide (1st edition) pgs 49-50 courtesy of Mike Butkus
• Forum discussion
  • [1]