This specific component is designed for Pentacon Six (P6) mount systems and is commonly used with Kiev 88 cameras that have been modified to accept P6 lenses (often referred to as Kiev 88CM or modified Kiev 88).Key Details: It is an extension tube used for macro photography to reduce the minimum focusing distance of a lens, allowing for extreme close-ups.Mount Compatibility: It features the Pentacon Six breech-lock bayonet mount. This allows it to be used with a variety of Soviet and East German lenses from manufacturers like Arsenal (Kiev) and Carl Zeiss Jena. Hartblei, a company known for producing high-quality modifications and accessories for Soviet medium format cameras, as well as specialized tilt-shift lenses.