C33, CSS AM41b, 1940-41 - Hong Kong Airmails, 30c, narrow type, Die 1, unwatermarked, in block of 164x4) with printer's imprint and plate number BC1.5

C33, CSS AM41b, 1940-41 - Hong Kong Airmails, 30c, narrow type, Die 1, unwatermarked, in block of 164x4) with printer's imprint and plate number BC1.5