A holding frame of a lens unit has a frame main body of a cylindrical shape, which corresponds to the shapes of lenses. The wheels are disposed on the bottom of the main body. The inner ring raceway surface of the inner ring is provided with a black oxidation coating, and a rolling contact surface of each cylindrical roller is provided with a diamond-like carbon coating. 1, A is selected from a group consisting of Sc, Y, La, Yb, and Lu, and M is selected from a group consisting of Sc, Y, La, Yb, and Lu. The boom and stem can pivot clockwise andor counterclockwise, manually and independently or can be coupled to automatically pivot together. The invention also relates to new compounds of formula, their preparation, use and compositions comprising said compound.