The ratcheting mechanism allows the nut to be tightened or loosened with a reciprocating motion, without requiring that the wrench be removed and refitted after each turn. A small lever on the ratchet head switches the wrench between tightening and loosening mode. The sockets are attached to the ratchet through a square fitting that contains a spring-loaded ball detent mechanism to keep the sockets in place. This drive fitting is in the size 1/2 inch. Despite being denominated in inches, these are international standards and no metric counterparts exist.