This is Mystery in Space 4, published by Mimosa (SA Magazine Co) +/- 1960.
It reprints the cover and the following 2 stories from DC Comics' Mystery in Space 49 (1958):
"The Sky-High Man!"
"The 24,000 Hour Day!"
24 pages, full-colour, newsprint stock cover and interior pages.
Here is the cover of issue 4 (notice the faint letters 49 still present on the cover next to "No. 4") and DC Comics' original cover:
Mimosa Mystery in Space Series