We can date this pattern to between 1944 and 1949, thanks to a combination of the postmark on the envelope and the fact that the sizing complies with commercial standard CS13-44.
This vintage pattern is complete, precut (i.e. cut by the factory during production), unprinted and appears to be factory folded (i.e. never used). Instructions and original mailing envelope are included. Pattern pieces are in excellent condition. Envelope is in fair condition.