Design of a product line of keys for a major global manufacturer ASSA ABLOY. During the design process, we placed emphasis on increasing the product usability. Due to limited dimensions of the product, it was necessary to pay attention to the minimal details. Thanks to the atypical and robust design, the comfort of use significantly increased. The main task of the key is to prevent slipping between the fingers when handling it. This was achieved thanks to the special “S” shape and the narrow horizontal ridges at the contact points. We wanted to achieve a symmetrical distribution of force on the key blade during rotation. Using the special “S” shape, we have reduced the risk of putting too much pressure on one side only and thus breaking the key. We drew inspiration from an aircraft propeller, which functions with the same logic of force distribution at the curved ends of the blades during rotation. The unifying design is ready for further expansion and application to all key models, from the basic to the most luxurious ones, which combine modern materials. Empty surfaces can be used for a logo or inscription placement.