The Grapple Gun, also called the Grappling Gun or Grapnel Gun, is a line launching, multi-purpose, highly versatile, and handgun-like device used by Batman and Slipknot. He has multiple devices in his possession, which are used as both a means of transportation and a weapon.
The gun fires a retractible, detachable line with a mechanized, magnetic, hooked or clawed end, which Batman utilizes to traverse Gotham City, escape danger and remain hidden from foes, all while allowing him to scale rappel, swing, catapult, or slingshot himself along structures or across gaps. It allows him to ascend and descend, much like an elevator or pulley system, at a harmless rate. It consists of a spool of cable, a winding device, and reloading feature.
Once it is shot a surface, it can pull the user at great speed towards their target and can quickly retract into the device once the user's destination is reached. This can be done in rapid succession, with the device being able to fire again instantly after retracting, with the manner of which the user is pulled through the air being similar to flight. Batman even managed to grapple away from a charging Doomsday, as well as several of the monster's huge heat blasts. The line can pull great amounts of weight, as Batman can use it to slowly descend several stories. However, the speed he is pulled to his target can seemingly be changed by him, allowing him to reach his destination softer and smoother in certain situations.
It can also be used to pull on an enemy with great force, enough to stun and daze them or to injure them, with the end of the line also acting like a harpoon that pierces the flesh of a target. The line could even send people flying through the air towards the user due to the force it exerted when retracting, which allowed Batman to strike his airborne target unopposed. The protrusion at the base of the gun's grip also makes it ideal to be used as a blunt weapon in close-quarters combat. It can also be used as a lasso, with Batman tying the line to Superman's leg and, with the strength of his Armored Batsuit and the line being pulled by the gun's internal mechanisms, slung him around a large corridor and into several pillars. Its internal mechanisms result it the line being able to pull and launch not only people, but also large and heavy objects such as a wooden crate, allowing Batman to tether one and catapult it across a room into an opponent.
Batman would later develop a second, heavy duty grapnel gun for him to utilize whilst wearing the far heavier Armored Batsuit.