An adaptor for optically connecting fiber optic devices, such as cable assemblies, together. The adaptor includes: a body (3) having first and second receiving formations (15,17), the first receiving formation (15) is arranged to receive a first fiber optic connector (19), the second receiving formation (17) is adaptable between first and second configurations, wherein in the first configuration the second receiving formation (17) is arranged to receive a second fiber optic connector (23), and in the second configuration is arranged to receive a ferrule (46).