The Synchron classic features a new compression molded eva midsole which is current in most modern running shoes. The dual density construction remains true to the original version from the early 1990s. The upper materials have been improved to premium pigskin suede from synthetic overlays while the original mesh appearance remains true to the era. To modernize the silhouette, Karhu makes the air cushion technology both visible and functional in the outsole. Most importantly, Karhu keeps the unique Synchron classic lacing structure which served as a way to tighten the forefoot upon repeated use.