My wife wanted to bring down a replacement Hybrid to stick in her "Florida bag" ... we each have set of NJ clubs and FL clubs so we don't have to lug them back and forth each month. I went to a local Golfsmith store and they were nice enough to give me a long, skinny golf club shipping box. We put the club in the box, taped it up, and had no problem whatsoever having it placed with our luggage for the flight to FLL.
Incidentally, whenever someone asks my superb golfer-wife "What's your handicap?" ... she just smiles, turns and points at me!
