Abstract: A coupling mechanism for use with flexible hose or tubing in which axial compression forces are applied to the end of the hose or tubing in order to provide the coupling action. The coupling mechanism includes a nipple having a head at the free end thereof surrounded by a collar having an inwardly extending abutment member at the opposite end thereof from the free end of the nipple. The end of the flexible hose or tube is received over the nipple and within the collar with a close fit. Upon axial movement of the collar with respect to the nipple toward the free end thereof, the abutment member on the collar will apply axial compression force to the end of the hose or tubing causing the wall at the end of the hose or tubing to expand into sealing and gripping relation with the nipple and collar. Means for forcing the collar to move axially of the nipple upon rotation of the collar and to selectively maintain the collar at a given point in the axial movement thereof are provided.