Wheels for under your shoes, these are heel wheels or heel wheels. Heel wheels are the predecessors of the Heelys, where the Heelys have fixed shoe sizes and the heel wheels are mounted under your own shoe.
You mount them around your heel and therefore also under your heel. There is no real name in Dutch so they are called Rollers or Heelys. Heel Wheels is the best name yet.
Because the heel wheels are only mounted under the heel of your shoe, you can still walk somewhat on the front of your shoes and gain speed to roll.
The heel wheels can be adjusted in size and made to fit any children's shoe. So they can grow over the years.
The wheels of the heel wheels are quite large, approximately 70mm. They are well mounted and have a hardness of approximately 80A. The wheels have a lot of grip.
Because the wheels are mounted on the side of your foot, you stand close to the ground and fairly stable. Not everyone experiences stability the same...
A rubber plate is mounted on the underside of the chop wheels that can be used to brake. This brake plate is replaceable.
Chop wheels have been around for a long time and their popularity varies from year to year. I expect that the wheels under your shoe will never disappear, just like the pogo and the unicycle. A few years ago a YouTuber, Enzo Knol, took a few of these wheels out of his old closet and tried them out on YouTube. For a few weeks they suddenly became popular again in a certain scene...
Streetsurfshop initially sold Wheel Wheels from PLWS (Play in Wheels) and these were of very good quality. Unfortunately they are no longer available. The Hudora Heel Wheels are also of good quality, just like the Razor. However, you do not always have to purchase the most expensive brand to have fun with wheels under your shoe