Yamoto: 21mm Socket 3/8" Square Drive These 3/8in. square drive, bi-hexagon sockets possess a 12 point side drive design that gives a higher torque than normal sockets, will grip worn nuts and will not round off existing nuts. All sockets have a ball-retaining groove on each face of the square drive, which ensures a positive fit with accessories and the bi-hexagonal design means the socket requires only a one-twelfth turn to engage the next point of the socket. Available in a range of metric lengths, each socket is manufactured from chrome vanadium steel, chrome plated with a mirror finish. Features and Benefits 12 point bi-hexagon side drive design gives a higher torque than normal sockets All have a ball-retaining groove on each face of the square drive, which ensures a positive fit with accessories The bi-hexagon design means the sockets require only a one-twelfth turn to engage the next point of the socket for less user effort when turning Manufactured from chrome vanadium steel