Concise in Japan[1] still make circular slide rules (the 300, 270N, 28N 27N). I bought a couple from them a few years ago. Good quality, and work well. [1] htt

Concise in Japan[1] still make circular slide rules (the 300, 270N, 28N 27N). I bought a couple from them a few years ago. Good quality, and work well. [1] https://www.sliderule.tokyo/products/list.php https://www.sliderule.tokyo/products/list.php