Q: What material are kettlebells made of? A: The internal weight stack of the kettlebell is constructed from durable solid steel, while its PP shell is crafted from die-cast aluminum. Additionally, the outer shell of the kettlebell is made of high-quality ABA plastic for enhanced durability and safety. Q: What should I pay attention to when using this LIFERUN Adjustable Kettlebell Set? A: During use, first ensure that the warning mark is accurately aligned with the base groove. Before attempting to lift the kettlebell, double-check that the weight numbers are properly aligned with the red indicator arrows to guarantee safe and stable operation. Q: Will the weights shift during use? A: No. The safety lock engages automatically when you lift the kettlebell, keeping plates secure. Just follow the manual/video for correct assembly.