Each book is an over sized digest measuring 6 1/4 x 8 1/2 inches.
The artwork is signed "mcguckin jr.". This is likely an artist named Malcolm Leland McGuckin Jr. The two books that may exist are advertised as Diamonds of Death by Borden Chase and A Grave Must be Deep by Theodore Roscoe. Both stories were also serialized in Argosy All-Star Weekly in the 1930s.