Allen Wrench Tool

allen wrench
A hex key (also known by various synonyms) is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head (internal-wrenching hexagon drive).
A hex head wrench
An L-shaped metal bar with a hexagonal head at each end, used to turn bolts and screws having hexagonal sockets
a wrench for Allen screws

tool
A device or implement, esp. one held in the hand, used to carry out a particular function
an implement used in the practice of a vocation
A thing used in an occupation or pursuit
A person used or exploited by another
drive; "The convertible tooled down the street"
instrument: the means whereby some act is accomplished; "my greed was the instrument of my destruction"; "science has given us new tools to fight disease"