Allen is a brand of hand tools, most widely recognized for its wrenches, known generically as "Allen wrenches". As a brand, it is owned by Apex Tool Group.
Allen Manufacturing Company Inc advertisement for the Allen Safety Set Screw, a brand of set screw, in the Automobile Trade Directory, January 1913.
Originally named Allen Manufacturing Company, the business produced hexagonal set screws and wrenches to fasten them. The terms "Allen wrench" and "Allen key" are derived from the Allen brand name and refer to the generic product category "hex keys".
W.G. Allen filed the first related patent in 1909 for its recessed hex-driven safety screws, a safety improvement over fasteners which protruded from machinery.
Apex Tool Group currently manufactures Allen-branded products in Dallas, Texas and Shanghai, China. They are made in L-key, folding, and T-handle styles.