First Day of Issue = September 5, 1933
Size: 37.00 mm x 23.00 mm
Quantity printed = 9,920
Perforated 10.00 x 11.50
Print method: Lithography

The surtax was for wounded Latvian aviators. The plane looks like an English Gloster VI.

Watermark



Catalog numbers
Scott CB22a
Michel LV 229B

For more information check out the links below
Gloster VI
Latvian airmail semipostal stamps
Latvian aviation