Coughtrie bulkheads

The left and middle bulkheads are PY10's. These are the much rarer variant featuring the opal and clear prismatic plastic bowls. Production was brief, hence they are getting impossibly rare. I knew of 4 clear prismatic examples, however they were removed 6 years ago. I had never seen an opal version until I first got this one.
In comparison the SY10 with its glass shade has been in production for around 50 years, and is still made today. They are also in very high demand due to their industrial looks.