Porto Rico Postal Envelope Used in the Philippines

1901, JANUARY 21: NVA CACERES, CAMARINES SUR to MANILA
Backstamped MANILA, P.I. / REC'D. / JAN 25.

EXTREMELY SCARCE

To date only 6 Puerto Rico #U-3 postal envelopes used in the Philippines
have been recorded. The above is one of two used in NUEVA CACERES.
The other four used in MANILA.