Wearing A Pocket Watch
The classic way to wear a pocket watch is at the end of a chain (called a fob) in your waistcoat pocket. The fob should pass through the button holes in the middle and terminate in a pocket on the other side, anchored by another object, maybe a cigar cutter.
T-bar chains mean the pocket watch can be worn without an additional object. The T-bar at the end of the chain holds the chain in the button hole.