Batman’s utility belt is one of the most notable pieces in his arsenal. Holding batarangs and other weapons, one of the most interesting pieces is the one specifically made to use against Superman.
Lex Luthor, Superman’s arch nemesis, realized long ago that Kryptonite was the one thing that could bring Superman to his knees. In order to safeguard himself, he had a ring made out of the lethal material and wore it at all times. Lex’s safety plan backfired, though, when the radiation from the ring gave him cancer, leading to the amputation of his hand. After Lex’s (apparent) death from the disease, Superman got hold of the ring but obviously couldn’t keep it without causing serious harm to himself. He decided to give the ring to the one person whom he could trust to kill (or weaken) him if he ever went rogue—his partner in justice, Batman.
Batman keeps the ring with him at all times, stored in a lead-lined box on his utility belt. He has actually had to use it on a couple of occasions; one of the most memorable was in the “Hush” series, when Batman had to use the ring to battle Superman who had been put under Poison Ivy’s spell.