This one showed up in an online auction awhile back.
Ordinarily I’m not interested in a pencil unless it’s marked with a name, but perpetual calendars are a pretty cool feature and besides the fact that it’s a great looking pencil, even though it isn’t marked I can tell you with absolute certainty who made this one:
Here’s our mystery pencil flanked by a pair of Dur-O-Lite pencils from the mid-1920s. They have identical nose cones and the tops are nearly identical. The top example shows that Dur-O-Lite used the same plastic, and the bottom one illustrates that the company used the same clip.
The perpetual calendar example has a little nicer metal work just beneath the cap. I’m surprised Dur-O-Lite didn’t mark this one; the only reason I can imagine why it wasn’t is that the calendar feature was right where the company’s imprint normally goes.