Abstract: An accessory for enabling an adjustable wrench to function as a measuring device is disclosed, the accessory comprising a planar, flexible, durable, adhesive-backed, L-shaped member having a short base leg and an integral elongate measuring leg bearing length-indicating indicia. The L-shaped member is adapted to be disposed upon an adjustable wrench such that the base leg is affixed to a side face of the wrench's fixed jaw and the measuring leg is affixed to the track in which the wrench's movable jaw travels. A supplemental reference member including a reference mark is disposed upon the movable jaw. A kit comprised of an L-shaped member and a reference member or, alternatively, a pair of mirror-image L-shaped members marked with different dimensional units, along with a pair of supplemental reference members, is also disclosed.