Kevin Kowalski doesn't haphazardly throw his name on anything, so you know there's a reason he's all about these amazing SPF skateboard wheels. It's about quality.
Skatepark Formula (SPF) - Skatepark Formula wheels are made from a high quality urethane that was specifically formulated to resist flatspotting on slick or smooth surfaces while maintaining a higher rebound for a quicker response and a faster roll.
SPF wheels have a high resistance to abrasion without compromising hardness and slide ability. Skatepark Formula wheels grip better on slick surfaces and are almost impossible to flatspot.