I've never seen one like that before. Interesting..
It looks like someone used a file to enlarge the holes. The enlargements are irregular in shape. If they were perfectly rounded I would say it was a double stamping.
Quote from: Uncle Al on August 16, 2015, 07:59:47 PMIt looks like someone used a file to enlarge the holes. The enlargements are irregular in shape. If they were perfectly rounded I would say it was a double stamping. +1. Maybe the PO wanted to do a low and slow and filed two vents down to aid in air control.