A curable composition apportioned between at least one Part A and at least one Part B the Parts sealed within barrier means preventing contamination the at least one Part A comprising: (i) one or more alkenyl group containing prepolymers having at least one alkenyl group or moiety per molecule and the at least one Part B comprising: (ii) one or more SiH containing prepolymers having at least one Si H unit per molecule the composition additionally comprising: (iii) a catalyst for curing by addition of alkenyi containing prepolymer (i) to SiH containing prepolymer (ii) wherein prepolymer (ii) is substantially absent from Part A and prepolymer (i) is substantially absent from Part B methods for preparing the composition methods for sterilisation thereof medical and non medical use thereof a device incorporating the composition and a precursor therefor including its sterilisable precursor composition in particular a terminally sterilisable or terminally sterile composition for medical use particularly in wound therapy more particularly as a wound packing material which can be shaped and configured to the shape of a wound most particularly for application in negative pressure wound therapy (NPWT).
