The cover of Detective 185 (July 1952) asks, what is the secret of Batman’s utility belt? The story by David V Reed and Dick Sprang answers that – his secret identity is inside.
While he doesn’t go so far as to sew labels into it, Batman does create a disc with his name and address. Incidentally, this is one of the extremely rare times Wayne Manor is given a specific address, 224 Park Drive.
Batman puts the disc in the belt and, wouldn’t you know it, loses the belt on the very next adventure.
A young boy finds it, but not the hidden disc. He replaces the useful stuff with twigs and rocks, and then loses it as well. It passes to a beggar and a rich man, before Batman finally gets on its track. But so do some hoods who have learned it’s secret as well!
Batman tricks them with a second belt, and his identity is saved.
Not bad for a story about a belt.