Assembles around the rod to form the L-ring and probably protects the motor/basal body from shearing forces during rotation. The basal body constitutes a major portion of the flagellar organelle and consists of four rings (L,P,S, and M) mounted on a central rod. Belongs to the FlgH family. Brucella species display species-specific inactivation of flagellar genes and are consequently nonmotile.