This is a porcelain "wall tube" for the entry of a wire into the building, then into the "knob and tube" style wiring. The "bell" end with the pink stripe would be located outsude, and pointing down to keep the rain out. Is this one common or rare, and what would be the estimated value of this one?

Update 4/13/07: I now have two of these, the stripe is slightly more pink than red on the "newer" one.