An assembly comprises first connection units attached to a shelf and second connection units attached to cards, respectively. Each first connection unit holds at least one first optic fiber, while each second connection unit holds at least one second optic fiber. The first connection unit is connected to the second connection unit so that the first optic fiber is connected to the second optic fiber. Each first connection unit comprises a body and an optic connector. Each body is floatingly supported by the shelf. Each optic connector is floatingly supported by the corresponding body. The double floating-support structure allows "blind mate" connections between the first and the second connection units.