 These ink droplets are measured in pica-litres and a print done at 200dpi will look more defined if it is printed with smaller ink droplets when compared to a machine laying down bigger ink droplets.The primary print head technologies used in ultra-wide format digital outdoor printing comes down to a few print head manufacturers worldwide including (but not restricted to) Piezo, Seiko and Spectra as the primary competitors and their print heads are used in most machines from a variety of manufacturers.They have their pros and cons and Piezo appears to focus more on the higher resolution side of the industry whereas Seiko and Spectra-Polaris tend more towards the robust, high production capabilities required in a manufacturing environment.