A cap for overfitting a nozzle having an elongate nozzle body; the cap having an elongate cap body with a longitudinal axis, and an outside surface and an inside surface. The cap body has closed end and an open end, with an at least one sidewall. A housing of the cap has an open end. The cap is for receiving and overfitting the nozzle body of the nozzle. The cap has three elongate spaced apart wing portions each having a wing profile each forming part of the outside surface of the cap. Each wing runs from the mouth of the cap to the closed end thereof, and each contiguous with the next so that an exterior face of one wing portion together with an exterior face of an adjacent wing portion form one continuous concave surface between each wing portion and the adjacent one. The cap has a part-helical, or skewed profile, which gives a visual indication of the direction of removal of the cap from the nozzle. A nozzle has matching depressions, which come into register with the concave surfaces of the cap. The assembly of cap over nozzle is suitable as a closure for a container holding curable product such as adhesive. A locking ring may be provided on the tube for locking a nozzle to the tube.