Chemtoy Corp., a Chicago-based toy firm formerly known as Chemical Sundries, made inexpensive rack toys including these Superman figures. Standing about 4″ tall, they are made of very cheap plastic with minimal paint decoration and no articulation, and were available in three different styles: Clark Kent changing into Superman, Superman breaking chains, and Superman that looks like he’s pounding his chest with his fist. Most of these were sold loose out of a display box, but K-mart, then known as Kresge, was a large enough toy buyer to get Chemtoy to put them on blister cards with a pre-printed price tag.
Chemtoy also sold Batman and Robin figures in a similar style. If you look at the Clark Kent photo below, you’ll notice a thin light blue and white stripe along the left side. That’s actually part of the background of the Batman Chemtoy card; Chemtoy had the display cards printed on the same press sheet and just miscut this one.
Fun fact Chemtoy also made one of the biggest fad toys of the 1970s: The Lemon Twist.