Measuring Tool That Identifies the Sizes of Bolt Heads and Nuts. The Wrench iD+ is a measuring tool that identifies sizes of bolt heads and nuts displaying the exact size wrench/socket. Also identifies inside and outside diameters of piping and other related objects. Comes complete in a form-fitted 7.5″ x 4.25″ x 1.75″ plastic case along with a CR2032 Battery. Features 3 Functions: Wrench iD – Identifies Wrench/Socket sizes in SAE and Metric 1/4in & 6mm through 2 1/8 in & 54 mm ranges. Outer Dimensional Measurements – in SAE and Metric 0 in & 0 mm through 2 1/8 in & 54 mm ranges. Inner Dimensional Measurements – in SAE and metric 1/2 in & 12.7 mm through 2 19/32 in & 66 mm ranges. Additional Features: LED light, Recall last size, Automatic shut off, Zero/recalibration, For precise measurements every time, Digital Display, Sizes in SAE and Metric. Perfect for: Professionals, Mechanics, Carpenters, Plumbers, Electricians, Do it Yourselfers, Farmers/Ranchers.