The Sonar Zen wheel by Radar is an inexpensive wheel used mostly for skating outdoors or jam skating. This is a relatively soft wheel that smooths out bumps on asphalt, sidewalks, or concrete. All Radar Zen wheels are available in 8 colors and you can mix/match colors if you like. Zen wheels are sized at 62mm x 32mm (kind of small) with 85A hardness (pretty soft to absorb outdoor conditions). You can use these wheels as an inexpensive add-on to your rink, jam, or dance skates if you feel like a little outdoor skating. You can use these wheels inside, but they might feel a little soft and slow.
The hardness on the Zen wheel is 85A, so it’s just hard enough to handle the rough outdoor terrain and soft enough to “give” when skating over curbs, bumps, or cracks in the road. These wheels are comparable to the Atom Pulse outdoor wheels, though the pulse wheels are a bit more “heavy duty”. Sold in 4 packs.