This is Blackhawk Giant Edition 3, published by Mimosa (SA Magazine Co) +/- 1963-1964.
It reprints the cover and the following 2 stories from DC Comics' Blackhawk 186 (1963):
"The Super Blackhawks of the Secret Dimension"
"The Riddle of the four clues"
Also reprinted is the following 2 stories from DC Comics' Blackhawk 109 (1957):
"The Avalanche King"
"The Raid on Blackhawk Island"
48 pages, colour cover, black-and-white interior pages (259x179mm).
Here is the cover of issue 3 and DC Comics' original cover:
Mimosa Blackhawk Giant Edition Series