The Flexaret IV was essentially the same as the Va but had a Metax Shutter (B, 1-1/400 sec) which was made domestically (instead of in Germany). Early Flexaret IV camara's had black leatherette but this changed to grey later on. Like the Va it had to option to use 35mm film with an adaptor that has to be installed inside the camera.
For filters Meopta broke away from the 30mm push on filters used on the Flexaret II - Va, they were now a special 2 lug bayonet called the B36 bayonet, only Meopta has made filters like that. Besides standard colour filters Meopta also delivered Closeup lenses for the Flexaret VI, VII and Standard with the B36 bayonet. 2 sets have been made, the first one is a 0.33 meters to 0.5 meters and the second set consists out of a 0.5 meters to 1 meter close up lens. Both closeup lenses came as a couple, since a TLR has 2 lenses. The flat one fits the taking lens while the thicker one was meant to fit on the viewing lens. The closeup lens for the viewing lens has parralax correction, there is a white dot on the lens and this has to face upwards to achieve the correct parralax correction.
The nameplate of the Flexaret VI reads Flexaret Automat (in constrast to to more sober Flexaret on previous models) but since there is no difference in automation compared to the Flexaret V it was more of a cosmetic change probably to boost sales.