Rosenberg, Klein & Bilker
Construction toy block and connector set
 A construction toy block set including a plurality of toy block elements respectively made of flat shape, a plurality of swivel connectors, and a plurality of fixed connectors, the block elements having pins and coupling recesses for coupling to one another directly, and retaining slots for coupling to one another by the swivel connectors or the fixed connectors, the swivel connectors being adapted for connecting the block elements together, permitting them to be turned relative to one another, the fixed connectors being adapted for connecting the block elements together and preventing them from being turned relative to one another. 
A A
A63H A63H
inventional inventional
Jin-Su
Liu