Flex sockets, also known as universal sockets, are hinged in the middle and can rotate and accommodate most angles to tighten and loosen fasteners in tight spaces that can’t be reached with a regular socket. They have an enclosed head that fits around and grips the entire head of the fastener so the socket won’t slip off. These universal joint sockets require a hand drive tool such as a ratchet or breaker bar to turn the socket and rotate the fastener. Drive tools have a square nub called the drive that fits into the same size drive end of the socket for secure attachment to the drive tool. Sets come with an assortment of sockets for a range of fastener head sizes.