Answer: A Kryptonite Ring

Over the years, Batman has packed a whole lot of stuff into that handy utility belt of his. In fact, it’s tough to find something that hasn’t ended up squirreled away in a compartment or two. There was even a time when he kept a can of shark repellent in there (Batman issue #117, 1958, for the curious).

But perhaps the most peculiar item in Batman’s belt is a little lead-lined pouch with a ring made out of Kryptonite that Batman keeps around explicitly for putting the beat down on his best buddy Superman. Why have a backup plan to beat up your best pal? Because when your best pal is a nearly unstoppable super-strong alien, sometimes you need to save him from himself (and everyone else in the process). For example, in Batman #612, DC universe villainess Poison Ivy puts a pheromone-powered spell on Superman. The only way to put a stop to the Man of Steel’s rampage was a good old fashion slug across the face with a Kryptonite-powered punch.

While nobody wants to see Superman suffer, a good friend knows when to keep you out of the fight (and save the city in the process).