Belgium: First airmail label

Here is the very first airmail label from Belgium.

Year: 1927, Gummed. Günter Mair's catalogue no: - BEL-A-1a, perforated 11, sheets of 64(4x16), paper with watermarks, black/grey-blue, 4****

Year: 1927, Gummed. Günter Mair's catalogue no: - BEL-A-1b, imperforated , sheets of 64(4x16), paper with watermarks, black/grey-blue, 4****