It is necessary to buy it if you want to keep fit. Whether skateboarding or kettle bell, the function is to keep fit or lose weight, and at the same time make the muscles stronger and more stylish. You can buy one separately, such as a slider. Because when skateboarding, the muscles of the whole body move in an orderly way, not just to strengthen the waist. Besides skateboarding and kettlebells, many fitness methods are worth doing, such as skipping rope every day, for example, running two kilometers every day. As long as you keep exercising 15 minutes or more, you can exercise. And stick to it, only long-term persistence can see the effect of fitness. I bought a lot of equipment, but if I don't stick to it for a long time, I can't exercise, but my weight will rebound quickly. For kettlebells and skateboards, skateboarding is more important than kettlebells. Skating exercises both waist strength and arm strength, which is equivalent to running in action. Because the legs must be constantly bent and stretched.