Our aim is to develop a notion of safety contracts and related reasoning that supports the reuse of software components in and across safety-critical systems, including support for certification related activities such as using the contract reasoning in safety argumentation. In this paper we introduce a formalism for specifying assumption/guarantee contracts for components developed out of context. We are utilising the concepts of weak and strong assumptions and guarantees to customise ne-grained contracts for addressing a broader component context and specification of properties for speci c alternative contexts. These out of context contracts can be conveniently instantiated to a speci c context, thereby providing support for component reuse.