Plethysmograph

A plethysmograph was an instrument for measuring variations in the size of an organ. On Jedha, G2-1B7 used one such device to track variations on Saw Gerrera's lung capacity.Star Wars: Rogue One: The Ultimate Visual Guide
==Sources==
*Star Wars: Rogue One: The Ultimate Visual Guide 
==Notes and references==
==External links==
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Category:Medical technology