These bronze mirrors with geometric designs were found in Jeongam-ri, Ganghyeon-myeon, Yangyang-gun, Gangwon-do. Two knobs are attached to the edge of the back. Bronze mirrors with this type of geometric design (mostly with converging triangular straight lines) are a more advanced version of mirrors with a coarse design. These particular mirrors are presumed to have served as ritual implement symbolizing the sun as well as fulfilling their usual function.