Made of pressed steel, with double ball bearing in the swivel head, strong central kingpin, ball protection by the special top plate and ball disc design. The special Blickle dynamic riveting process of the swivel head results in minimal swivel head play and smooth rolling characteristics with an increased service life achieved by the work hardening of the ball race grooves. Bolted wheel axle. Zinc-plated, blue-passivated, Cr6-free. Made of high-quality, impact-resistant nylon.