Smart services are a combination of physical and digital services that are based on the data of a physical product. As a result, smart services are integrated product-service systems with a focus on digital, data-based service components. The challenge in research is currently to combine theoretical considerations in the field of servitization (market pull), cyber-physical systems (technology push) and practical requirement of companies. This contribution shows the results of a study of companies that have successfully implemented smart services. Ten case studies were analyzed with the focus on manufacturing companies that have transformed a classic product into a smart product-service system. The result is a set of building blocks like monitoring, alerting and x-on-demand. These building blocks can be used to plan new smart services based on an existing product and to implement them based on reference solutions that are assigned to each building block.