No experience here, just reading from a monograph
Comments need confirmation.
It would be identical to MALAYA Chop Number 1
Approx 13mm x 19mm
Excepting that has a DOUBLE LINED FRAMEand all corners are sharply bevelled
Bib: W.H. Adgey-Edgar (Undated)
Monograph from the generous gift of SCF "Calstamp"
Chop reads "Seal of the Post Office of Malay Military Department"
Engraved? carved in wood, the inner line is much thinner, and sometimes has breaks, and in many cases parts are completely missing.
March 16th 1942