Kryptonite lock

Bicycle lock

Kryptonite is an Allegion-owned brand of bicycle lock for securing a bicycle to a pole or other fixture, when the owner wants to leave the bicycle in a public place. The basic design, made of hardened steel of circular cross section bent into a U-shape with a removable crossbar, has been emulated by numerous other manufacturers, and adapted with variations in size and shape for other applications, such as locking motorcycles.

This keyword could refer to multiple things. Here are some suggestions: