A cap 10 for a container comprises an annular collar 12 with a longitudinal axis (X figure 7) and a diameter perpendicular thereto. A seal 14 comprises two seal elements 16,18,20 which cooperate to form a generally cylindrical seal member locatable in the collar 12 with the seal elements 16,18,20 in contact with one another in a plane parallel to the longitudinal axis. At least one of the seal elements 18,20 comprises at least one opening 52,54,56 therethrough. The openings 52,54,56 are configured to receive the tubes of a medical tube set (figures 8-10) and the cap 10 can be constructed with different combinations of seal members 16,18,20 to provide a different number of openings into the container. A kit of parts and a tube set are also claimed.
