[en] Cherenkov shower full absorption γ-spectrometer employing KRS-6 crystal (monocrystal with 80% of TlCl and 20% of TlBr) is designed with a view to ensure higher accuracy of 1 gev energies. The spectrometer is graduated on monoenergetic single electrons within a range of energies of 400-1200 Mev. Energy resolution of the spectrometer varies within this range from 19.5 up to 13%