ESATTO 4″ is the large dimensions robotic microfocuser that we designed for observatory class telescopes or for astrographs that need for large free aperture, like the Takahashi FSQ-106. Compared to the smaller models, ESATTO 4″ offers a larger free aperture of 102mm, a longer draw tube travel of 35mm and a higher payload capacity of 10 kg, always with the incredible technical features of all the ESATTO focusers: resolution of 0.04 microns per step, USB-C port for computer control, WiFi connection with included Virtual HandPad and ARCO rotator port.