Extremely solid and durable construction, you can find the opinion that it is an indestructible camera.
"The Fed 5 is one of the most feature packed Soviet rangefinder which does not require a battery. It is virtually undestroyable, I bet it is going to stay operational way after man kind extinct and the cockroaches rule the world. Since it has no battery an EMP blast cannot ruin it. A nuclear winter could not make any difference neither as the kit lens (Industar-61L/D) is already rumored to be slightly radioactive."
In FED-5, mainly cosmetic changes were introduced in comparison to its predecessor. The frame counter was covered, the read out of the light meter was easier to read and the window of the light meter sensor with the window of the viewfinder / rangefinder was unified. Technically corrected the inconvenience in the way the film was rolled, now you could do it with the pull-out knob, also added an electrical connector in the foot of the flash to support the newer types of lamps. In addition, the frame counter resets itself after opening the rear flap.