No. 15 Material:
No. 15, NLSize:
Pat. Reg. - Breg. HS Style:
Breg LS Unadj Htg a few made PSB + *85 17 jewel Source:
I found the above information based on the serial number, which seems to indicate that it's a size 18. But the above information seems incorrect inasmuch as mine is 17 jewels and does not reference P.S. Bartlett.