In this paper, we propose a conceptual model for tunable security services. The aim of the model is to provide a tool that can be used to describe and analyze such services in a structured and consistent way. The proposed model can thus serve as a basis to examine the possibilities available for constructing tunable security services based on current and future networking standards and to identify missing requirements. It can also be used to describe and compare previous research results. In the paper, four different use cases are presented that illustrates the powerfulness of the proposed model.