The Grapple Gun is a line cable firing device used to assist Batman in his transportation needs. By firing a cabled hook onto a building he can ascend and scale the various buildings or swing from them across Gotham City. It is also used by him as a tool to catch objects and draw them closer or reach them. A larger scaled version is mounted underneath the Batmobile. Both Robin and Batgirl are also seen using grapple guns in their crime-fighting efforts.
The rope is resistant enough to support Batman's weight even from large distances and also two or three people hanging from it.
A special feature of Batman's grapple gun was the electric cord that can be activated to bust metallic doors open.