The aim of the REIS project is the design, development and construction of a portable Runaway Electron Imaging Spectroscopy (REIS) system for use in medium size tokamaks. The REIS detects the visible and infrared synchrotron radiation spectra emitted by runaway electrons (RE) during the various phases of a plasma discharges including the runaway plateaus following disruption events. The REIS-Extended is an upgrade of the first system in order to cover spectra from 0.4 up to 5µm of wavelength. REIS-E is composed by 4 spectrometers (VIS, NIR, MIR for forward plasma view and a VIS spectrometer for backward view) coupled with an incoherent bundle of optical fibers collecting the light from the system head. The latter is made of 2 wide-angle lenses connected to the fibers and to the fast CCD camera, that allows tokamak's images recording from the vessel. In this session we will discuss the details of the diagnostic and we will show the preliminary results of the last FTU data campaign in autumn 2019, with shots recorded at 4 and 5.5 T. A first analysis approach was done using Synchrofit tool, a python software for fitting data with mono energetic model.