The device (1) is made of a special resin and assembled of several parallel positioned semi-circular pockets (3) to be combined with complementary parts. The upper edges are wedge-shaped (4) for a better fit. The inner surfaces (5, 6) serving as paths are of a spherical shape and provided with thick walled lateral edges (1a). Transversally positioned grooves (8) are provided for the storage of a lubricant as well as a groove (9) located at the bottom.
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