Aspect oriented programming promotes the separation of the different aspects of a system into their natural form. Synchronisation is an important aspect of concurrent object-oriented systems, but treating synchronisation as a single monolithic aspect leads to inflexibility and limited possibilities for reuse. We suggest that synchronisation has a number of different aspects, and introduce the 'synchronisation rings' model which allows the aspects of a synchronised object to be specified independently. By separating the different aspects of synchronisation we can provide flexible, generic implementations of common synchronisation constraints, which can be reused in many different contexts