I found this on the Southwest website, I hope it helps: Fishing tackle box and fishing rod, Fishing rods must be encased in a sturdy, cylindrical fishing rod container. This container must be able to withstand normal Checked Baggage handling without sustaining damage to the rod. Oversize charges only apply if the fishing rod container is over 91 inches in length and/or more than three inches in diameter. A fishing tackle box must be a suitable, sturdy, and securely closed container. When substituting a fishing rod and/or fishing tackle box for a free checked bag, Southwest Airlines allows for one fishing rod container and one tackle box to count as one checked item, even if they are packed and tagged separately. This one item can be a substitute for one checked bag.
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