New Standard Traveler missing serial number?

[IronHammer]

On my traveler set I recently acquired, I notice there is no serial number stamped into the head of the razor nor on the bottom knob portion. How would I narrow down a date for this razor then? I thought all Gillettes were serial numbered up to the 1930's.

Or maybe my traveler set was made after 1930?

Edit: Here is picture of the base plate:

 

[AsylumGuido]

New Improved razors made between Oct. 17, 1927 and Aug. 28, 1928 did not have serial numbering.

 

[IronHammer]

New Improved razors made between Oct. 17, 1927 and Aug. 28, 1928 did not have serial numbering.

Ahh! Guido, thank you so much for being a treasure trove of razor knowledge. So I have a 1927 or 1928 Traveler set. Very groovy! It always nice to know exact dates of things