This model features an aluminum frame, which is rare for kids' inline skates. The frame has five mounting holes for the wheels, allowing for either a three-wheel setup with a maximum wheel size of 80mm, or a four-wheel setup with a maximum wheel size of 72mm. The skates come with 80mm wheels installed by default. They effectively transfer the kicking force to the ground, enhancing the enjoyment of skating. The size can be adjusted in four stages by pressing the button on the side of the boot, accommodating the child's growth. A heel brake is installed on the right boot only. Three short shafts are included, which are needed if you remove the brake or want to use a four-wheel setup. I bought them for about 20,000 yen. The skating is smooth, the speed is good, and they are very quiet. Inline Skates