Small. 10-13mm in metric and 7/16" to 1/2" in US sizes. Mouth width 10mm; overall length 155mm. VDE (Verein Deutsche Elektriker) insulated self setting spanners. Individually tested at 10.000 Volts; in accordance with IEC 60900; which ensures safe working with live wiring up to 1000 Volts. The sliding function allows safe opening of the jaws. Contacting the non-insulated jaws is not required. The 6004 series Joker is similar to a regular adjustable wrench; and that is also where the similarity stops. The Joker is auto-adjusting and with its smooth parallel jaws it offers a secure grip on bolt and nuts; without causing damage. Additionally it has an actual built-in ratcheting function with a 30° back-pivoting angle.