Allen Wrenches, also called hex keys, Allen keys or hex wrenches, are a six-sided wrench designed to drive an internal hexagonal drive style. Hex keys are most recognized by their L shape wrench. These size sided L shape wrenches have many benefits making them the tool of choice for many who use socket cap screws. Due to the similar look of most hex keys, most find a labeled set to be the most efficient. The term Allen is actually a manufacturing company who makes these wrenches, the generic term for an Allen wrench is a hex key.