Abstract: A combination square comprising a blade; and a head defining a slot in which said blade is at least partially received, said blade extending generally perpendicular to said head; wherein said head is divided into a first portion and a second portion, said first portion defining said slot, wherein said first and second portions are pivotally joined to each other by a pivot assembly, said pivot assembly defining an axis that extends parallel to said blade, whereby said second portion may be rotated about said axis.