Manfrotto 047-2 Alu-Core for Uncored Paper or Cloth - 9' (2.7 m)

One cross bar.

Yes, this is compatible with the Impact Varidrives.

To attach backdrops/paper without a core to the crossbar.

This Alu-Core is only for reinforcing the cardboard core on seamless paper or vinyl background rolls while using a manual drive system. What you could use is the Savage Multiple Polevault System (12.6' Width), BH # SABGSMPV which includes the hardware to hold up 3 rolls at a time on the same stand. https://bhpho.to/3MLp3mX

Once the two pieces are joined together, an Allen wrench is provided to expand the set screw which locks the two pieces into place. Loosen the screw with the Allen wrench to take them apart.

The Manfrotto 047-2 Alu-Core for Uncored Paper or Cloth - 9' (2.7 m) is not designed to allow more than two to be attached together, so it cannot be made longer. If you need a longer pole, I suggest going to a hardware store and getting a steel pole that is long enough for your needs.

There is the Manfrotto 047-3 Alu-Core for Uncored Paper or Cloth - 12' (3.6 m), BH # MA0473 which can help. https://bhpho.to/3b9QVTV

The Manfrotto 047-2 Alu-Core for Uncored Paper or Cloth - 9' (2.7 m) does fit onto a roll of seamless. But it is loose and will not work properly when using it with a roller system.