1. Shirtless and semi-nude covers and interior illustrations. Hundreds of muscular teenage boys and men on display, many more than in the American adventure boys series.
They were playing sports, camping, fighting monsters. They were alone and in pairs. Their muscles glistened in the Christmas firelight.
2. The stories inside did not involve the dating, romances, and overall girl-craziness that obsessed American teen stories in the 1950s and 1960s. They were about boys meeting, being rescued by, and establishing permanent relations with other boys and men.
For instance, in a story in Monster Book for Boys ("monster" means "big"), sixteen-year old Keith is living quietly on a farm in Devon, longing for “companionship and fun,” when he stumbles upon Count Max Von Staubnitz, “a pleasant-looking, rather dandified young man" (i.e., he's gay). After an acquaintanceship lasting less than five minutes, the Count invites Keith to come along on his quest to retrieve a secret formula from enemy agents, resulting in many last-minute rescues and many opportunities to praise Keith’s “youthful muscles” and “muscles like steel" (i.e., he thinks that Keith is hot). Then, when the crisis is resolved, the Count, blushing and stammering like a shy schoolboy, invites Keith to live on his estate in Central Europe (i.e., he wants a permanent partner, not just a fling).