Standard - Your classic wheel shape, it's not built to excel in specific scenarios like a narrow or wide wheel, but it's appropriate for most situations. If you're new to skating this is where you want to start.
Treaded - Treaded wheels provide improved grip and traction on smooth surfaces.
99a - Best used in pools and parks with a little more grip than harder wheels, and a little more slide than softer wheels. Ideal for moderately skilled riders who also want to skate street when needed. Hard enough that sliding is a breeze while soft enough for a smooth roll and plenty of grip.
Most urethane skate wheels generally range from 75a-101a, the numbers increase with the hardness of the wheel.
|Riding Surface (mm):||20.5||22.0||21.0||19.0|
|Suggested Riser Size (in):||N/A||N/A||N/A||1/8|