This is Detective Comics 3, published by Mimosa (SA Magazine Co) +/- 1960.
It reprints the cover of DC Comics' Detective Comics 271 (1959).
The stories reprinted are:
"Crime Rides the Rails" from Batman 121 (1959)
"The Trial of Chief War Cloud!" from All-Star Western 105 (1959)
"Mask of Mystery!" from Western Comic 74 (1959)
24 pages, full-colour, newsprint stock cover and interior pages.
These titles were printed in a smaller size (253x173mm) compared to the original DC Comics title.
The printing reproduction from the original was very good quality.
Here is the cover of issue 3 and DC Comics' original cover:
Mimosa Detective Comics Series