Available with Laser Etched Logo cores. Made from Certified 6061 aluminum extrusion and machined to shape. The Urethane is Hand Poured in Holland according to our own proprietary formulas. The 2-Layer ( Dual Layer) design with this "undersized" HOLLOWTECH core, is one of our UNIQUE designs and inventions. The advantage of the Dual Layer is the wheels will get MORE rebound, MORE grip and MORE smoothness when riding. Back are some of our original model names: Snowballs (Silver or Black with White urethane), Panthers (Silver or Black with Black urethane), Sewercaps (Silver or Black with Grey urethane). Each Model comes with it's own urethane Hardness. SNOWBALLS: just ABOVE the "standard" hardness; PANTHERS: just above the Snowballs Hardness; SEWERCAPS: The HARDEST scooter wheels out there! Our unique 2-layer(Dual Layer) system is often copied but never equaled!