A medical device has a base having an internally tapered wall mounted to a neck of a tube holder that has a reverse taper, so that rotation of the base relative to the neck may be effected with a controlled drag to provide a smooth and secure relative rotation. The base may be rotated relative to the holder by rotationally moving a needle protection housing hingedly attached to the base. The housing may be rotated to any orientation relative to the tube holder so long as a torsional force greater than the predetermined friction between the tapered surfaces is applied thereto. The base is designed to have a ring at its base that biases against the base of the neck in a self-adjustable manner. Other devices may also be fitted with reverse tapered complementary connection fittings to securely couple to each other.