SPI-SKW-6263. Diameter: 53-56mmDurometer: 101aFormula Four SeriesConical Full ShapePack of 4Formula Four Performance UrethaneFlatspot resistance, durability, controllable grip and a smooth, anti-stick slide is what Spitfire had in mind when they created these wheels. Tested in Spitfire's labs and tested on the streets by Spitfire's riders, these wheels aim to combine all the desired properties of a performance wheel, without sacrificing any attribute at the expense of another. Spitfire's Conical Full shape has a wider riding surface and cutaway design to give more control and lasting speed everywhere. Skate harder, skate faster, burn four-ever! Spitfire Formula Four Conical 101D Skateboard Wheels Natural/Green 53mm