First Day of Issue = April 30, 1920
Size: 27.50 mm x 32.00 mm
Quantity printed = 953,007
Perforated 10.00 x 11.50

SATVERSMES SAPULCES PEEMIŅAI translates to IN MEMORY OF THE CONSTITUTIONAL ASSEMBLY

Catalog numbers
Scott 70
Michel LV 42A

For more information check out the links below
First Constitutional Assembly
Latvian Parliament and Governments 1920-1934