While TESS-W can determine the night sky brightness in a broadband (panchromatic) it is interesting to determine the brightness in several bands to also get insight into the colour of the night sky. This is a step forward because variations in brightness and colour of the sky is a key observation when determining the impact of light pollution when a retrofit (change of lamp technology) is on the way.
TESS-4C is similar to a TESS-W but has 4 channels. The data are feed to the STARS4ALL repository and can also be read with local apps in your computer.

First version of TESS-4C showing the filter holders for custom 1 1/4 filters

Second version of TESS-4C and photometric bands.

The user can select photometric bands using 1.25" filters. The filter set transmission used allows to determine red, green (synthetic) and blue and also TESS-W band and UVIR650 nm band. For more information read "TESS-4C filters LICA report"

You can browse data in real time for stars703 at Sierra Nevada at the grafana panel
More info about setting up and connection at Observatorio Remoto blog