Storage is a huge factor in ensuring the quality of your kybun or Joya Shoes. The rubber-like materials, such as the PU we use in the kybun and Joya soles, provide cushioning when you step on them, which is what makes the shoe so comfortable. Over time, without regular wear, the materials lose their elasticity and become porous and brittle - especially if the shoe sits around unused for a long time. You can compare the PU sole to a rubber band, if the rubber band doesn’t get stretched, it will become brittle and break. kybun and Joya shoes should therefore be worn regularly, then the soft-elastic sole will retain its comfortable properties for a long time without material fatigue.