The porthole is designed to ensure observation of the Earth's surface from the edge of the cosmonave during orbital flight.
The porthole is composed of a special safety glass that withstands repeated overloads during the rocket's firing, the freezing of the cosmic void during the orbital flight, and the heat of the plasma during the descent of the descent device from cosmic orbit.
The ‘Ksomos2120’ spacecraft was launched from the ‘Plessezk’ spaceport and returned to Earth after the end of the space flight.
It bears a certificate issued by the Commander of the Cosmic Units of the Ministry of Defence of the USSR Colonel gneral V.L.Ivanov.
Base measurement: 7.5 cm