Fiberglass wheels [also known as fibers] are typically made of fiberglass sheets and resin. The main purpose is to try to provide a sliding experience to the skater.

These wheels will provide the most consistent sliding experience and work on every smooth surface I have skated on with no tradeoffs for the slides that I attempted to resolve.  When it comes to sliding, fiber is king.

There is a ton of feedback from fiberglass wheels.  Being a solid mass, vibrations travel unfettered into the plate of the skate.  To the uninitiated, it may be sensory overload.  Because of this, we strongly recommend checking the skate surface and exercising caution the first one or two times around a new rink.  (This is good practice going around any rink in fibers just to train and remind the brain that the rules are a little different.)

Fibers have a reputation of being an "advanced" wheel.  I don't believe they are an advanced or difficult wheel to skate, they do have their own style of skating.  While wheels with grip allow the skater to have wide shapes, slippery wheels ask the skater to stay over their boot more often than not.

Fiber wheels will 100% change the way you skate because slip at most occasions. Pushing off will initiate a slide from the pushing foot (and possibly the stable one depending on the skater's weight and sturdiness), tight corners will need a change in approach, no aggressive pivots turn into slides and aggressive braking techniques turn into slides. When I skate my fibers under unpressured situations, I tend to skate slower because when I push, I cannot transfer power efficiently.  In high-pressure situations (e.g., international parties, I will skate faster to keep pace with the crowd but will constantly use sliding moves to shave off speed.

Sliding styles are enabled by fiberglass wheels.