6904-421 "KENTO" quick adjusting wrench. A handful of these wrenches are known, and they appear to be based on Allen's 1920 design patent, although the details are unknown. The name in the arrow-shaped trademark could be "Kento", or possibly "Kent, O" or even "KO Ent (Enterprises). It?s a weird design - when the handle is turned to one position the jaw slides freely, turning the handle locks it and provides for fine adjustment. Nickel is partly worn. Good (JSM072) 50 - 100