British Guiana: Airmail labels

Here is my first airmail label from this terittory also it's very first issue from British Guiana.

Year: 1930, Ungummed. Günter Mair's catalogue no: - BGA-A-1a, perforated 11, sheets of 30(5x6)
with 5 pairs tête-bêche, black/blue-grey, 4****