Dropping a Cow Magnet Down a Metal Tube

[fester225]

I came across a couple of cow magnets a while back.

When you drop a cow magnet down the center of a vertical piece of steel conduit, it doesn't drop as fast as it usually would.

When you drop a cow magnet down the center of a vertical copper plumbing pipe (closer fitting than the conduit), the magnet drops considerably slower than it usually would.

When you drop a cow magnet down the center of a vertical copper plumbing pipe which has been placed inside the steel conduit, the magnet drops still more slowly.

What will slow the magnet's drop the most? Would it be thicker copper pipe, a closer fitting, thicker walled steel pipe, or is the combination of copper and steel pipes a magic combination?

 

[Per Oni]

I can't help but seeing the magnet getting stuck to the steel conduit.
A copper pipe will slow the magnet down considerably, the thicker the pipe wall the slower the magnet falls. Also a narrower fit will slow it more. I see it this way: the more volume of magnetic field is flowing through copper, the bigger the current is generated in the pipe, and therefore the more the magnet slows down.