There is provided a novel fitting having male and female ends and a tapered internal luer-type seal. The male fitting end has a periphery upon which is mounted at least one boss. The female fitting end has a slot into which the boss may be inserted. At the bottom of the slot is a stop to limit the insertion depth of the boss. The male and female ends may then be rotated relative to each other to move the boss into a window on the female end. The window has a frame and the upper frame is angled slightly, corresponding to the boss, which serves to draw the male end farther in to the female end. The window has a side frame that stops the rotational movement of the boss. When the movement of the boss is stopped, the male and female tapers are in substantially leak-free contact. There is also provided a closed suction catheter using the novel fitting, such that the catheter may be easily and quickly removed and replaced.