Powerslide SWELL Black Fire. The Powerslide SWELL Black Fire is a revolutionary inline skate designed specifically for intense fitness training. This skate features an anatomically shaped shell with flex cuts in the ankle area and a recall fit with memory foam to provide outstanding comfort and maximum support. The new upper material combines our stretchy and ventilated Powerknit with welded TPU reinforcements to enhance responsiveness and stability. The highly abrasion-resistant TPU material protects the toes and side plates from falls and wear, thereby extending the lifespan of the skates to withstand even the most demanding training sessions. The Trinity frame with a 3-point attachment helps you reach new levels of performance.