Bayonet V adapters
This mount was known in USSR as Bayonet V.
It was used on such medium format cameras as Kiev-88, Salyut-S and Zenit-80 manufactured in 1972-1980.
Like many other technical things, it was copied from foreign camera. This time from Hasselblad (models 1000F and 1600F had the same mount in 1948-1957).