Flex head wrenches have heads that pivot in the stirrup to allow the wrench to be used at different angles, increasing the wrench's reach.
The stirrup is made from the base of the head or the end of the shaft. A collar at the end of the shaft allows the head to have two profiles.
All types of wrench heads can be of flexible head design. One of the most common wrench designs is the combination wrench with an open-ended fixed head and a flexible ring head with a ratchet (see illustration). What is a combination key?).
Flex head and socket wrenches are also common. Socket sockets are similar to box wrenches and fit over the top of the head of the fastener to completely enclose it during use. Scaffolding wrenches are an example of flexible head socket wrenches (see What is a Scaffolding Wrench?).
