There are certain styles of skating and certain terrains where additional flex is required to allow the skater to better manage energy. So, back to the lab we went and the end result is the two-piece, EMT flex technology, which is based on the hollow core. EMT has that extra 'snap' providing the skater some more energy when skating corners or skatng the double push. EMT originally was created for track wheels but also the marathon skater like the EMT core a lot. F1 | 124g | EMT CORE